0000000000828316

AUTHOR

H. J. Elmers

showing 46 related works from this author

Bulk spin polarization of magnetite from spin-resolved hard x-ray photoelectron spectroscopy

2021

Physical review / B 104(4), 045129 (1-10) (2021). doi:10.1103/PhysRevB.104.045129

Materials scienceCondensed matter physicsSpintronicsSpin polarizationPhotoemission spectroscopyFermi levelPolarization (waves)530chemistry.chemical_compoundsymbols.namesakeCondensed Matter::Materials ScienceX-ray photoelectron spectroscopychemistrysymbolsddc:530Spin (physics)Magnetite
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Monitoring surface resonances on Co2MnSi(100) by spin-resolved photoelectron spectroscopy

2015

The magnitude of the spin polarization at the Fermi level of ferromagnetic materials at room temperature is a key property for spintronics. Investigating the Heusler compound Co$_2$MnSi a value of 93$\%$ for the spin polarization has been observed at room temperature, where the high spin polarization is related to a stable surface resonance in the majority band extending deep into the bulk. In particular, we identified in our spectroscopical analysis that this surface resonance is embedded in the bulk continuum with a strong coupling to the majority bulk states. The resonance behaves very bulk-like, as it extends over the first six atomic layers of the corresponding (001)-surface. Our study…

Condensed Matter - Materials ScienceMaterials Science (cond-mat.mtrl-sci)FOS: Physical sciencesddc:530Condensed Matter::Strongly Correlated Electrons
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Compositional dependence of element-specific magnetic moments in Ni2MnGa films

2009

Element-specific magnetic moments were investigated for epitaxial Ni2Mn1+xGa1−x and (Ni2MnGa)1−x(Co2FeSi)x Heusler films using x-ray absorption spectroscopy and x-ray circular magnetic dichroism in transmission. The epitaxial films of the Ni2MnGa-derived compositions were prepared by dc-sputtering on Al2O3 substrates at 773 K. X-ray diffraction confirms a (1 1 0) oriented growth. An increase in the Mn concentration reduces the magnetic spin moment of both Mn and Ni. An increase in the content of Co2FeSi in the Ni2MnGa compound leads to an increase in the Mn and Ni spin moments and to a decrease in Tm for 5% Co2FeSi and finally to a suppression of the phase transition for 20% Co2FeSi. The or…

Phase transitionAcoustics and UltrasonicsAbsorption spectroscopyMagnetic momentMagnetic circular dichroismChemistryAnalytical chemistryContext (language use)Sputter depositionCondensed Matter PhysicsSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsSpin magnetic momentCrystallographyCircular magnetic dichroismJournal of Physics D: Applied Physics
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Itinerant half-metallic ferromagnetsCo2TiZ(Z=Si, Ge, Sn):Ab initiocalculations and measurement of the electronic structure and transport properties

2010

This work reports on ab initio calculations and experiments on the half-metallic ferromagnetic Heusler compounds ${\text{Co}}_{2}\text{Ti}Z$ $(Z=\text{Si},\text{ }\text{Ge},\text{ }\text{Sn})$. Aim is a comprehensive study of the electronic-structure and thermoelectric properties. The impact of the variation in the main group element $Z$ on those properties is discussed. X-ray diffraction was performed on the compounds and the lattice parameters are compared to other ${\text{Co}}_{2}$-based compounds. Hard x-ray photoemission measurements were carried out and the results are compared to the calculated electronic structure. The experimentally determined electronic structure, magnetic propert…

PhysicsCondensed matter physicsFerromagnetismAb initio quantum chemistry methodsElectrical resistivity and conductivitySeebeck coefficientLattice (order)X-ray crystallographyCurie temperatureElectronic structureCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsPhysical Review B
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Large area conductive nanoaperture arrays with strong optical resonances and spectrally flat terahertz transmission

2017

Using simple and inexpensive nanosphere lithography, we produce large, centimeter-squared sized thin golden films patterned with a hexagonal array of nanoapertures with controllable dimensions on the order of 100–300 nm, spaced by a 350–375 nm pitch distance. The optical transmission spectra of our samples are dominated by the resonant plasmonic features in the spectral range 500–700 nm, caused by the nanostructure in the film. At the same time, the transmission at terahertz (THz) radiation is as high as ∼10% and is spectrally flat. Our measurements are in agreement with finite difference time domain simulations. Such thin metal hole array films allow for very efficient injection of optical…

0301 basic medicineNanostructureMaterials sciencePhysics and Astronomy (miscellaneous)Terahertz radiationbusiness.industryNanophotonicsFinite-difference time-domain methodPhysics::Optics02 engineering and technologyPhysik (inkl. Astronomie)021001 nanoscience & nanotechnology03 medical and health sciences030104 developmental biologyNanolithographyOpticsTransmission (telecommunications)OptoelectronicsNanosphere lithography0210 nano-technologybusinessPlasmonApplied Physics Letters
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Interface magnetization of ultrathin epitaxial Co2FeSi(110)/Al2O3films

2007

Element-specific magnetic properties of ultrathin epitaxial Co2FeSi(110) films were measured using x-ray magnetic circular dichroism (XMCD). The epitaxial Heusler films were grown by RF magnetron sputtering on substrates. The magnetization of thicker films as determined by XMCD is smaller than expected for a half-metallic material. In addition, the magnetization decreases considerably for films thinner than 10 nm. The thickness dependence of the magnetic moment can be described by introducing a certain number of dead layers representing a deficiency of magnetization at the interfaces. Quantitative evaluation results in a dead layer thickness of 0.8 nm at room temperature, consisting of a te…

MagnetizationMaterials scienceAcoustics and UltrasonicsMagnetic momentCondensed matter physicsMagnetic circular dichroismDead layerSputter depositionCondensed Matter PhysicsEpitaxyTemperature inducedSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsJournal of Physics D: Applied Physics
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Momentum-resolved photoelectron absorption in surface barrier scattering on Ir(111) and graphene/Ir(111)

2017

Physical review / B 96(15), 155108 (2017). doi:10.1103/PhysRevB.96.155108

Range (particle radiation)Materials scienceGrapheneScattering02 engineering and technologyPhotoelectric effect021001 nanoscience & nanotechnology01 natural sciencesMolecular physics530law.inventionMomentumElectron diffractionlaw0103 physical sciencesRectangular potential barrierddc:530010306 general physics0210 nano-technologyAbsorption (electromagnetic radiation)
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Correlation of local disorder and electronic properties in the Heusler alloy Co2Cr0.6Fe0.4Al

2007

For the fully ordered Heusler alloy Co2Cr0.6Fe0.4Al half-metallic ferromagnetism has been predicted. Local disorder other than the Al–Cr/Fe (B2)-type disorder is known to destroy the half-metallic bandgap. The usage of appropriate buffer layers improves the structural quality of thin films. We correlate the structural properties of thin magnetron sputtered films determined by x-ray diffraction with details of the x-ray magnetic circular dichroism spectra. From the value of the magnetic moment located at the Cr atom and features of the Co absorption spectra we conclude that the buffer layers lead also to an improvement in the local atomic order. The atomic ordering gradually approaches the l…

Materials scienceAcoustics and UltrasonicsAbsorption spectroscopyMagnetic momentCondensed matter physicsMagnetic circular dichroismBand gapAlloyengineering.materialCondensed Matter PhysicsSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsCondensed Matter::Materials ScienceFerromagnetismAtomengineeringThin filmJournal of Physics D: Applied Physics
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Disentangling the Mn moments on different sublattices in the half-metallic ferrimagnet Mn3−xCoxGa

2011

Ferrimagnetic Mn3−xCoxGa compounds have been investigated by magnetic circular dichroism in x-ray absorption (XMCD). Compounds with x>0.5 crystallize in the CuHg2Ti structure. A tetragonal distortion of the cubic structure occurs for x≤0.5. For the cubic phase, magnetometry reveals a linearly increasing magnetization of 2x Bohr magnetons per formula unit obeying the generalized Slater–Pauling rule. XMCD confirms the ferrimagnetic character with Mn atoms occupying two different sublattices with antiparallel spin orientation and different degrees of spin localization and identifies the region 0.6<x≤0.8 as most promising for a high spin polarization at the Fermi level. Individual Mn moments on…

Physics and Astronomy (miscellaneous)Magnetic momentSpin polarizationCondensed matter physicsChemistryMagnetic circular dichroismFermi levelCondensed Matter::Materials ScienceMagnetizationTetragonal crystal systemsymbols.namesakeFerrimagnetismFormula unitsymbolsCondensed Matter::Strongly Correlated ElectronsApplied Physics Letters
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Dünne epitaktische Filme der Heusler-Phase Co2Cr0,6Fe0,4Al

2004

Inorganic ChemistryCondensed matter physicsChemistryZeitschrift für anorganische und allgemeine Chemie
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Localized magnetic moments in the Heusler alloy Rh2MnGe

2009

X-ray magnetic circular dichroism (XMCD) of core-level absorption (x-ray absorption spectroscopy, XAS) spectra in the soft x-ray region has been measured for the ferromagnetic Heusler alloy Rh2MnGe at the Rh M3,2 and Mn L3,2 edges. The ratio of Rh and Mn spin moments amounts to 0.05 which is smaller than the ratio of 0.1 determined by a local density approximation electronic band structure calculation. We have found that the orbital moments of the Rh 4d and Mn 3d states are very small. The observed Rh 2p XAS spectrum can be understood on the basis of the Rh 3d partial density of unoccupied states as is typical for metals. The observed features of the Mn 2p XAS and XMCD spectra are dominated…

X-ray absorption spectroscopyAcoustics and UltrasonicsCondensed matter physicsAbsorption spectroscopyMagnetic momentMagnetic circular dichroismHeisenberg modelChemistryCondensed Matter PhysicsSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsCondensed Matter::Materials ScienceMagnetizationFerromagnetismCondensed Matter::Strongly Correlated ElectronsLocal-density approximationJournal of Physics D: Applied Physics
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Element-specific magnetic moments from core-absorption magnetic circular dichroism of the doped Heusler alloyCo2Cr0.6Fe0.4Al

2003

The magnetic circular dichroism (MCD) of core-level absorption (x-ray absorption spectroscopy, XAS) spectra in the soft x-ray region has been measured for the ferromagnetic Heusler alloy ${\mathrm{Co}}_{2}{\mathrm{Cr}}_{0.6}{\mathrm{Fe}}_{0.4}\mathrm{Al}$ at the Co, Fe, and Cr ${L}_{II,III}$ edges. The comparison of XAS spectra before and after in situ cleaning of polished surfaces revealed a pronounced selective oxidation of Cr in air. For clean surfaces we observed a MCD for all three elements with Fe showing the largest moment per atom. The MCD can be explained by the density of states of the $3d$ unoccupied states, predicted by linear muffin-tin orbital atomic sphere approximation. For …

Condensed Matter::Materials ScienceX-ray absorption spectroscopyMaterials scienceAbsorption spectroscopyFerromagnetismMagnetic momentCondensed matter physicsMagnetic circular dichroismAtomAnalytical chemistryAbsorption (logic)Electronic band structurePhysical Review B
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Element-specific magnetic properties of mixed 3d−4f metallacrowns

2018

Single molecule magnets comprising rare earth metals are of high interest due to the unquenched orbital moments of the rare earth ions that result in a large energy barrier for magnetization reversal. We investigate the magnetic properties of polynuclear $3d\text{\ensuremath{-}}4f15$-MC-5 metallacrowns using x-ray magnetic circular dichroism of powder samples at a temperature of 7 K in a magnetic field of 7 T. The sum rule analysis reveals element-specific spin and orbital moments. The magnetic moments of the $3d$ transition metal Ni(II) ions are coupled antiferromagnetically to each other and contribute only little to the total molecular moment. The spin and orbital moments of the rare ear…

PhysicsCondensed matter physicsMagnetic moment010405 organic chemistryMagnetic circular dichroism010402 general chemistry01 natural sciences0104 chemical sciencesMagnetic fieldDipoleMagnetic anisotropyMagnetZeeman energySpin (physics)Physical Review B
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Structural and Magnetic Dynamics in the Magnetic Shape Memory Alloy Ni$_2$MnGa

2014

Magnetic shape memory Heusler alloys are multiferroics stabilized by the correlations between electronic, magnetic and structural order. To study these correlations we use time resolved x-ray diffraction and magneto-optical Kerr effect experiments to measure the laser induced dynamics in a Heusler alloy Ni$_2$MnGa film and reveal a set of timescales intrinsic to the system. We observe a coherent phonon which we identify as the amplitudon of the modulated structure and an ultrafast phase transition leading to a quenching of the incommensurate modulation within 300~fs with a recovery time of a few ps. The thermally driven martensitic transition to the high temperature cubic phase proceeds via…

QuenchingPhase transitionCondensed Matter - Materials ScienceMaterials scienceKerr effectCondensed matter physicsPhononDemagnetizing fieldNucleationMaterials Science (cond-mat.mtrl-sci)FOS: Physical sciencesCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsCondensed Matter::Materials ScienceMagnetic shape-memory alloyMultiferroics
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Charge transfer and tunable minority band gap at the Fermi energy of a quaternaryCo2(MnxTi1−x)GeHeusler alloy

2010

We investigate the distribution of element-specific magnetic moments and changes in the spin-resolved unoccupied density of states in a series of half-metallic ${\text{Co}}_{2}({\text{Mn}}_{x}{\text{Ti}}_{1\ensuremath{-}x})\text{Ge}$ Heusler alloys using x-ray magnetic circular dichroism. The Co and Mn magnetic moments are oriented parallel while a small Ti moment shows antiparallel to the mean magnetization. The element-specific magnetic moments remain almost independent on the composition. Therefore, a replacement of Ti by Mn results in an increase in magnetization. The increase in magnetization with increasing $x$ follows the Slater-Pauling rule. The Fermi level decreases with respect to…

Materials scienceMagnetic momentCondensed matter physicsBand gapFermi levelFermi energyCondensed Matter PhysicsSemimetalElectronic Optical and Magnetic MaterialsCondensed Matter::Materials Sciencesymbols.namesakeMagnetizationsymbolsDensity of statesDirect and indirect band gapsAtomic physicsPhysical Review B
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Element-specific magnetic properties of Co2(Mn1−xFex)Si films probed by x-ray magnetic circular/linear dichroism

2011

Element-specific magnetic properties of epitaxial Co${}_{2}$Fe${}_{x}$Mn${}_{1\ensuremath{-}x}$Si/MgO(100) Heusler films prepared by laser ablation are measured by circular dichroism in x-ray absorption spectroscopy (XMCD). Surface and bulk magnetization of the 100-nm-thick films are equal as tested by comparing the total electron yield and transmission measurements and follow the generalized Slater-Pauling rule. For Co${}_{2}$FeSi, the large magnetization of 6 ${\ensuremath{\mu}}_{B}$ per formula unit indicates half-metallic behavior. Calculations using the local spin density approximation (LDA) result in a half-metallic band structure for this compound when an additional electron-electron…

Circular dichroismMagnetizationMaterials scienceAbsorption spectroscopyCondensed matter physicsX-ray magnetic circular dichroismFormula unitCondensed Matter PhysicsLinear dichroismElectronic band structureSpectral lineElectronic Optical and Magnetic MaterialsPhysical Review B
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Reorientation of magnetization states in Fe-nanostripe arrays on stepped W(110) caused by adsorption of CO, H2 and O2

1999

Abstract Fe-Nanostripe arrays of alternating double layer (DL) and monolayer (ML) stripes were grown on stepped W(1 1 0) surfaces by MBE. Magnetic properties were measured in situ in UHV using the polar and longitudinal magneto-optical Kerr effect (MOKE) during exposure to CO, H2 and O2. The longitudinal Kerr signal increases and the polar signal decreases with increasing exposure of all three gases. A sudden onset of perpendicular remanence was observed at exposures characteristic for each particular gas.

MagnetizationMagnetic anisotropyMaterials scienceKerr effectCondensed matter physicsMagneto-optic Kerr effectRemanenceMonolayerPolarCondensed Matter PhysicsMicromagneticsElectronic Optical and Magnetic MaterialsJournal of Magnetism and Magnetic Materials
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Temperature dependence of x-ray absorption spectra in the ferromagnetic Heusler alloysMn2VAlandCo2FeAl

2010

We investigate the temperature dependence of the spin-resolved unoccupied density of states (DOS) in ferromagnetic ${\text{Co}}_{2}\text{FeAl}$ and ferrimagnetic ${\text{Mn}}_{2}\text{VAl}$ epitaxial films on MgO(100) using x-ray magnetic circular dichroism. We observe an unexpected strong temperature dependence of the DOS beyond the change expected from the Fermi distribution function. An increase in spectral weight is observed for majority states below the Fermi energy in the case of ${\text{Mn}}_{2}\text{VAl}$ and for minority states above the Fermi energy in the case of ${\text{Co}}_{2}\text{FeAl}$. Reduced atomic order near the interface suppresses the unexpected temperature dependence…

Materials scienceCondensed matter physicsAbsorption spectroscopyMagnetic circular dichroismFEALFermi energyCondensed Matter PhysicsElectronic Optical and Magnetic Materialssymbols.namesakeFerromagnetismFerrimagnetismDensity of statessymbolsFermi–Dirac statisticsPhysical Review B
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Torsion oscillation magnetometry (TOM) of Fe films on Ni(111)/W(110) substrates

1999

Abstract Fe films 2–20 atomic monolayers (ML) thick have been deposited on Ni(1 1 1) films (4–60 ML) prepared on W(1 1 0) under UHV conditions. The Ni(1 1 1) films grow in a Nishijama–Wassermann orientation with a 3.6% lattice expansion along Ni[2 1 1] (‖ W[1 1 0]). On top of these slightly distorted Ni films iron is observed to grow preferentially in two mirror orientations. The saturation magnetization of these Fe films and the anisotropies of Fe/Ni bilayers have been studied using torsion oscillation magnetometry. The magnetization of the Fe films of 2.13 μB per atom is close to the bulk value of Fe. The out-of-plane surface (interface) anisotropy constant KFeNis=(−0.65±0.15) mJ/m2 of th…

Materials scienceCondensed matter physicsMagnetometerAnalytical chemistryTorsion (mechanics)Condensed Matter PhysicsLattice expansionElectronic Optical and Magnetic Materialslaw.inventionMagnetizationlawMonolayerPerpendicularAnisotropyAnisotropy constantJournal of Magnetism and Magnetic Materials
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Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording

2019

Journal of synchrotron radiation 26(6), 1996-2012 (2019). doi:10.1107/S1600577519012773

time-of-flight microscopeDiffractionNuclear and High Energy PhysicsMaterials scienceMicroscopePhoton550530 Physics02 engineering and technologyKinetic energy01 natural scienceslaw.inventionOpticslaw0103 physical sciencesddc:550HAXPES010306 general physicsInstrumentationMonochromatorRadiationk-spacebusiness.industry021001 nanoscience & nanotechnology530 PhysikResearch PapersBrillouin zoneWavelengthTime of flightBrillouin zone0210 nano-technologybusinessX-ray photoelectron diffraction
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Magnetism of metallacrown single-molecule magnets: From a simplest model to realistic systems

2018

Electronic and magnetic properties of molecular nanomagnets are determined by competing energy scales due to the crystal field splitting, the exchange interactions between transition metal atoms, and relativistic effects. We present a comprehensive theory embracing all these phenomena based on first-principles calculations. In order to achieve this goal, we start from the ${\mathrm{FeNi}}_{4}$ cluster as a paradigm. The system can be accurately described on the ab initio level yielding all expected electronic states in a range of multiplicities from 1 to 9, with a ferromagnetic ground state. By adding the spin-orbit coupling between them we obtain the zero-field splitting. This allows to in…

PhysicsCondensed matter physicsMagnetismExchange interaction02 engineering and technology021001 nanoscience & nanotechnology01 natural sciencesMagnetic anisotropyFerromagnetismSuperexchangeCrystal field theory0103 physical sciencesSpin model010306 general physics0210 nano-technologyGround statePhysical Review B
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Solvent-induced high-spin transition in double-decker 3d–4f metallacrowns

2019

Element-specific magnetic spin and orbital magnetic moments of $3d\text{\ensuremath{-}}4f$ double-decker metallacrown molecules have been investigated using x-ray magnetic circular dichroism. The double-decker metallacrowns comprise one rare-earth Gd(III) or Tb(III) ion embedded between two squared scaffolds of four Ni(II) ions. We observe a strong increase of the Ni(II) moments if the molecules are dissolved in methanol, indicating a spin crossover from a low-spin to a high-spin state. In contrast, dichloromethane does not change the spin state. This result is explained by a change of the coordination environment of nickel. The comparison of charge-transfer multiplet calculations with the …

Materials scienceSpin statesMagnetic momentMagnetic circular dichroismSpin transition02 engineering and technology021001 nanoscience & nanotechnology01 natural sciencesSpin magnetic momentCrystallographySpin crossover0103 physical sciencesCondensed Matter::Strongly Correlated Electrons010306 general physics0210 nano-technologyMultipletMetallacrownPhysical Review B
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Charakterisierung von dotierten Heusler-Verbindungen: Co2Cr1−xFexAl

2004

Inorganic ChemistryCrystallographyChemistryZeitschrift für anorganische und allgemeine Chemie
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Hosting of surface states in spin–orbit induced projected bulk band gaps of W(1 1 0) and Ir(1 1 1)

2017

Journal of physics / Condensed matter 29(25), 255001 - (2017). doi:10.1088/1361-648X/aa7173

PhysicsPhotonCondensed matter physicsSpintronicsField (physics)Band gap02 engineering and technologyPhysik (inkl. Astronomie)021001 nanoscience & nanotechnologyCondensed Matter Physics01 natural sciences530Brillouin zone0103 physical sciencesGeneral Materials Scienceddc:530010306 general physics0210 nano-technologySpin (physics)ExcitationSurface states
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Exchange coupling in the correlated electronic states of amorphous GdFe films

2013

The bulk sensitivity of hard x-ray photoelectron spectroscopy in combination with circularly polarized radiation of the P09 beamline at PETRA III enables the investigation of the magnetic properties of capped films. We have determined the temperature dependence of the magnetic circular dichroism in the Fe 2$p$ and in the Gd 3$d$ states in amorphous GdFe films. The magnetic dichroism reflects the stronger temperature dependence of Gd moments compared to Fe moments in agreement with mean-field models. We resolved the exchange split Gd 3${d}_{5/2}$ substates and found a significant temperature dependence of the splitting which is attributed to a temperature dependent part of the exchange energ…

Circular dichroismMaterials scienceCondensed matter physicsAbsorption spectroscopySpin polarizationPHOTOELECTRON-SPECTROSCOPYSPIN POLARIZATIONVALENCE STATESMagnetic circular dichroismExchange interactionCORE-LEVEL PHOTOEMISSIONLOCALIZED MAGNETIC SYSTEMSDichroismCondensed Matter PhysicsMAGNETOOPTICAL PROPERTIESX-RAY DICHROISMElectronic Optical and Magnetic MaterialsAmorphous solidCIRCULAR-DICHROISMANGULAR-DISTRIBUTIONX-ray photoelectron spectroscopyddc:530TRANSITION-METAL ALLOYS
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Electronic properties of Co2FeSi investigated by X-ray magnetic linear dichroism

2014

We present experimental XMLD spectra measured on epitaxial (001)-oriented thin Co$_{2}$FeSi films, which are rich in features and depend sensitively on the degree of atomic order and interdiffusion from capping layers. Al- and Cr-capped films with different degrees of atomic order were prepared by DC magnetron sputtering by varying the deposition temperatures. The local structural properties of the film samples were additionally investigated by nuclear magnetic resonance (NMR) measurements. The XMLD spectra of the different samples show clear and uniform trends at the $L_{3,2}$ edges. The Al-capped samples show similar behavior as previous measured XMLD spectra of Co$_2$FeSi$_{0.6}$Al$_{0.4…

Condensed Matter - Materials ScienceMaterials scienceMagnetic momentCondensed matter physicsAb initioAnalytical chemistryX-rayMaterials Science (cond-mat.mtrl-sci)FOS: Physical sciencesSputter depositionPhysik (inkl. Astronomie)Condensed Matter PhysicsLinear dichroismEpitaxySpectral lineElectronic Optical and Magnetic Materialsddc:530Deposition (law)
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Manipulation of antiferromagnetic domain distribution in Mn2 Au by ultrahigh magnetic fields and by strain

2017

Evidence for a spin reorientation in antiferromagnetic (AFM) Mn2Au thin films induced by high magnetic fields as well as by the application of in-plane mechanical stress is provided. The AFM domain population in the samples was investigated by resonant X-ray Magnetic Linear Dichroism (XMLD) measurements at the L3 edge of Mn using a variable linear polarization of the incident photon beam. As grown samples show no XMLD signal due to averaging over a random AFM domain distribution. After the exposure to a 70 T in-plane magnetic field a clear XMLD signal indicating the generation of a preferential AFM domain orientation is obtained. The same type of XMLD signal is observed when the thin films …

education.field_of_studyMaterials scienceCondensed matter physicsLinear polarizationPopulation02 engineering and technology021001 nanoscience & nanotechnologyCondensed Matter PhysicsLinear dichroism01 natural sciencesMagnetic fieldStress (mechanics)0103 physical sciencesAntiferromagnetismCondensed Matter::Strongly Correlated ElectronsGeneral Materials ScienceThin film010306 general physics0210 nano-technologyeducationSpin (physics)physica status solidi (RRL) - Rapid Research Letters
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Magnetic and structural investigations of ultra-thin Co–Fe alloy films on W(1 1 0)

2004

Abstract We investigated ultra-thin CoxFe1−x films on a flat and vicinal BCC W(1 1 0) surface with thicknesses between 1.8 and 7 monolayers (ML) using longitudinal Kerr magnetometry. We found a transition from magnetic bulk behavior between 3 and 4 ML to the monolayer. The maximum of the remnant Kerr signal that appears for thicker films at x=0.5 turns into a minimum for a sample thickness below 4 ML , while the specific Kerr-rotation per monolayer shows the well known bulk behavior. A similar magnetic behavior on the flat as well as on the stepped part of the substrate indicates that this is an intrinsic property. For x=0.5 the pseudomorphic monolayer is paramagnetic even when it is covere…

ParamagnetismMagnetizationKerr effectMaterials scienceFerromagnetismCondensed matter physicsMonolayerSubstrate (electronics)Thin filmCondensed Matter PhysicsVicinalElectronic Optical and Magnetic MaterialsJournal of Magnetism and Magnetic Materials
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Morphology and magnetism of Fe on vicinal W(110) surfaces with different step orientation

2000

Abstract Nanostructures of monolayer height of single-crystalline Fe(1 1 0) films were grown on stepped W(1 1 0) surfaces. The growth mode strongly depends on the step orientation of the substrate. Continuous stripes are formed at steps along the [1 0 0] direction whereas triangular shaped islands grow on substrates with [1 −1 0]-oriented step edges. No ferromagnetic order was found in submonolayer films grown on [1 −1 0]-steps. The nanostripe array on [1 0 0] steps shows a ferromagnetic phase-transition with a critical behavior different from the Ising-like phase transition observed for submonolayer films grown on smooth W(1 1 0). The magnetic easy axis in the samples is oriented parallel …

Phase transitionMagnetic anisotropyMaterials scienceCondensed matter physicsFerromagnetismMagnetismFilm planeMonolayerThin filmCondensed Matter PhysicsVicinalElectronic Optical and Magnetic MaterialsJournal of Magnetism and Magnetic Materials
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Microscopic origin of magnetic anisotropy in martensitic Ni2MnGa

2011

The microscopic origin of magnetic anisotropy in the shape memory alloy Ni${}_{2}$MnGa is investigated by means of x-ray magnetic circular dichroism in transmission mode. Field- and angle-dependent dichroism spectra of epitaxial Ni${}_{2}$MnGa(101)/MgO(001) films reveal pronounced differences for magnetization aligned parallel and perpendicular to the film plane. These differences are related to an anisotropy of the orbital magnetic moment in agreement with the observed out-of-plane magnetocrystalline anisotropy. The spectral variation of the x-ray absorption originates from changes in the spin-projected density of states when the magnetization vector is rotated from the easy to the hard ma…

Condensed Matter::Materials ScienceMagnetic anisotropyMagnetizationParamagnetismMaterials scienceCondensed matter physicsX-ray magnetic circular dichroismMagnetic momentAbsorption (logic)Condensed Matter PhysicsMagnetocrystalline anisotropyMagnetic susceptibilityElectronic Optical and Magnetic MaterialsPhysical Review B
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Oxidation-driven changes of the in-plane magnetic surface anisotropies of the Fe(110)/Al interface

2003

Abstract Thin epitaxial iron films grown on W(1 1 0) were covered by ultrathin epitaxial aluminium layers of varying thicknesses from 0.2 to 0.6 nm and subsequently naturally oxidized in situ with oxygen exposures up to 150 L. Correlations between the oxidation states of the Al covers and changes of the in-plane magnetic anisotropies at the Fe(1 1 0)/Al interface were discussed on the basis of results from X-ray photoelectron spectroscopy and longitudinal magneto-optical Kerr magnetometry measurements. The Al coverage decreases the second-order in-plane surface anisotropy of the Fe(1 1 0) surface. Whereas for the thinnest Al covers, the second-order in-plane magnetic surface anisotropy decr…

Aluminium oxidesMaterials scienceAnalytical chemistrychemistry.chemical_elementCondensed Matter PhysicsElectron spectroscopyElectronic Optical and Magnetic Materialschemistry.chemical_compoundMagnetic anisotropyMagnetizationNuclear magnetic resonancechemistryX-ray photoelectron spectroscopyAluminiumAluminium oxideAnisotropyJournal of Magnetism and Magnetic Materials
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Epitaxial films of the magnetic shape memory material

2007

Abstract By DC-sputtering from a stoichiometric target onto sapphire substrates we prepared epitaxial films of Ni 2 MnGa . X-ray diffraction in two circle geometry shows only the Ni 2 MnGa peaks corresponding to a (1 1 0) oriented growth on the (1 1 0) oriented sapphire substrate. Rocking curve scans shows that the out of plane orientation has a width of only 1 . 1 ∘ . By four circle X-ray diffraction we find an in-plane aligned growth. The Curie temperature as determined by SQUID magnetometry is 368 K. On cooling down the low field magnetization drops at around 260–280 K indicating the austenite to martensite transition. The presence of two different phases at high and low temperature also…

Materials scienceMagnetic momentCondensed matter physicsMagnetic circular dichroismSputter depositionCondensed Matter PhysicsElectronic Optical and Magnetic Materialslaw.inventionSQUIDMagnetizationNuclear magnetic resonanceMagnetic shape-memory alloylawSapphireCurie temperatureJournal of Magnetism and Magnetic Materials
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Néel Spin-Orbit Torque Driven Antiferromagnetic Resonance in Mn2Au Probed by Time-Domain THz Spectroscopy

2018

We observe the excitation of collective modes in the terahertz (THz) range driven by the recently discovered Neel spin-orbit torques (NSOTs) in the metallic antiferromagnet Mn_{2}Au. Temperature-dependent THz spectroscopy reveals a strong absorption mode centered near 1 THz, which upon heating from 4 to 450 K softens and loses intensity. A comparison with the estimated eigenmode frequencies implies that the observed mode is an in-plane antiferromagnetic resonance (AFMR). The AFMR absorption strength exceeds those found in antiferromagnetic insulators, driven by the magnetic field of the THz radiation, by 3 orders of magnitude. Based on this and the agreement with our theory modeling, we inf…

PhysicsCondensed matter physicsOrders of magnitude (temperature)Terahertz radiationPhysics::OpticsGeneral Physics and AstronomyResonance02 engineering and technology021001 nanoscience & nanotechnology01 natural sciences7. Clean energyMagnetic fieldNormal modeElectric field0103 physical sciencesAntiferromagnetismCondensed Matter::Strongly Correlated Electrons010306 general physics0210 nano-technologyExcitationPhysical Review Letters
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Strain detection in non-magnetic steel by Kerr-microscopy of magnetic tracer layers

2018

Abstract For many applications of steel, e.g. for the evaluation of the fatigue state of components or structures, the characterization of the microscopic strain distribution in the material is important. We present a proof-of-principle for the visualization of such strain distributions by Kerr-microscopy of ferromagnetic tracer layers on nonmagnetic steel sheets. The influence of indentation induced strain on the magnetic domain pattern of 20 nm Galfenol and Permalloy tracer layers on austenitic AISI 904L steel sheets was investigated. The obtained Kerr-microscopy images show a characteristic domain pattern in the strained regions of the steel sheets, which is consistent with a dominant ma…

010302 applied physicsPermalloyAusteniteMaterials scienceStrain (chemistry)Magnetic domainPattern formation02 engineering and technology021001 nanoscience & nanotechnologyCondensed Matter Physics01 natural sciencesElectronic Optical and Magnetic MaterialsFerromagnetismIndentation0103 physical sciencesComposite material0210 nano-technologyGalfenolJournal of Magnetism and Magnetic Materials
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Multidimensional photoemission spectroscopy—the space-charge limit

2018

New journal of physics 20(3), 033004 - (2018). doi:10.1088/1367-2630/aaa262

Free electron modelPhysicsPhotonPhotoemission spectroscopyFermi levelGeneral Physics and AstronomyFermi surfaceFermi energy02 engineering and technologyElectron021001 nanoscience & nanotechnology01 natural sciencesElectron spectroscopy530symbols.namesake0103 physical sciencessymbolsddc:530Atomic physics010306 general physics0210 nano-technology
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Thin epitaxial films of the Heusler compound

2005

Abstract We prepared thin films of the Heusler compound Co 2 Cr 0.6 Fe 0.4 Al with the B2 structure on a-plane (1 1  2 ¯  0) Al 2 O 3 by sputtering. Films grown at high temperatures ( T ⩾ 600 ∘ C ) on Al 2 O 3 are fully epitaxial with the (1 1 0) and (1  1 ¯  0) planes of the film parallel to the (1 1  2 ¯  0) and (0 0 0 1) planes of the substrate, respectively. These epitaxial films possess a higher surface roughness than films grown at room temperature. The films show nearly rectangular hysteresis loops with coercive fields of the order of 10 mT. Magnetooptical Kerr measurements show an in-plane anisotropy of the magnetization with the easy axis in { 0 0 1 } direction. Hall measurements s…

Materials scienceCondensed matter physicsSputter depositionengineering.materialCoercivityCondensed Matter PhysicsHeusler compoundElectronic Optical and Magnetic MaterialsMagnetizationMagnetic anisotropySputteringHall effectengineeringThin filmJournal of Magnetism and Magnetic Materials
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Magnetic properties of Co2Mn1−xFexSi Heusler alloys

2006

Co2Mn1−xFexSi Heusler alloys with Fe concentration x = 0–0.4 as prepared by arc melting show a L21 long range order for all Fe concentrations. Magnetic properties of Co2Mn1−xFexSi Heusler alloys were investigated by magnetometry and circular magnetic dichroism. The magnetization of the Fe doped Heusler alloys is in agreement with the Slater–Pauling values expected for half-metallic ferromagnets. Element specific magnetic moments as determined by x-ray absorption using the total electron yield method are in disagreement with theoretical predictions for x = 0 but approach the predicted values as the Fe concentration increases. Surprisingly small Fe concentration increases the magnetic moments…

Acoustics and UltrasonicsCondensed matter physicsMagnetic momentMagnetic circular dichroismChemistryMagnetometerElectronDichroismCondensed Matter PhysicsSurfaces Coatings and FilmsElectronic Optical and Magnetic Materialslaw.inventionMagnetizationFerromagnetismlawCircular magnetic dichroismJournal of Physics D: Applied Physics
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Enhanced orbital magnetic moments in the Heusler compounds ,,

2004

Abstract Using the magnetic circular dichroism in X-ray absorption at the L2,3-edges of the 3d-transition metals, we determined the element specific ratio between orbital and spin magnetic moment of the Heusler compounds Co 2 CrAl , Co 2 Cr 0.6 Fe 0.4 Al and Co2FeAl. The orbital magnetic moment per spin is large (0.1–0.2) compared to bulk values of Fe and Co metals.

Angular momentumMaterials scienceTransition metalCondensed matter physicsMagnetic momentMagnetic circular dichroismCondensed Matter::Strongly Correlated ElectronsAbsorption (chemistry)DichroismCondensed Matter PhysicsSpin (physics)Electronic Optical and Magnetic MaterialsSpin magnetic momentJournal of Magnetism and Magnetic Materials
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Tuning the hole injection barrier in the intermolecular charge-transfer compoundDTBDT-F4TCNQ at metal interfaces

2014

Molecular monolayers of the charge-transfer salt dithienobenzodithiophene-tetrafluorotetracyanoquinodimethane (DTBDT-F${}_{4}$TCNQ) have been deposited on C(R$15\ifmmode\times\else\texttimes\fi{}3$)/W(110), Co/W(110), and hcp Co(0001) using molecular beam epitaxy in an ultrahigh vacuum. The integrity of the deposited molecules has been confirmed by scanning tunneling microscopy. Scanning tunneling spectroscopy has been used to determine the energetic positions of the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbital of acceptor and donor in the pure and in the mixed phase. The mixed charge transfer phase exhibits a new HOMO close to the Fermi edge depicting a charge tra…

Materials sciencebusiness.industryBand gapScanning tunneling spectroscopyBinding energyCondensed Matter PhysicsElementary chargeAcceptorElectronic Optical and Magnetic Materialslaw.inventionCrystallographylawOptoelectronicsMolecular orbitalScanning tunneling microscopebusinessHOMO/LUMOPhysical Review B
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High-resolution hard-x-ray photoelectron diffraction in a momentum microscope—the model case of graphite

2019

New journal of physics 21(11), 113031 - (2019). doi:10.1088/1367-2630/ab51fe

DiffractionPhysicsMomentum (technical analysis)MicroscopeX-rayGeneral Physics and AstronomyHigh resolution530law.inventionlawHard X-raysddc:530GraphiteAtomic physics
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Broken symmetry states of metallacrowns: Distribution of spins and the g tensor

2019

PhysicsDistribution (number theory)SpinsQuantum mechanicsSymmetry breakingTensorPhysical Review B
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Epitaxial film growth and magnetic properties ofCo2FeSi

2006

We have grown thin films of the Heusler compound ${\mathrm{Co}}_{2}\mathrm{Fe}\mathrm{Si}$ by RF magnetron sputtering. On (100)-oriented MgO substrates we find fully epitaxial (100)-oriented and $L{2}_{1}$ ordered growth. On ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}(11\overline{2}0)$ substrates, the film growth is (110)-oriented, and several in-plane epitaxial domains are observed. The temperature dependence of the electrical resistivity shows a power law with an exponent of $7∕2$ at low temperatures. Investigation of the bulk magnetic properties reveals an extrapolated saturation magnetization of $5.0{\ensuremath{\mu}}_{B}∕\mathrm{f.u.}$ at $0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The films on $…

Materials scienceSpin polarizationMagnetic momentCondensed matter physicsMagnetic circular dichroismSputter depositionengineering.materialCondensed Matter PhysicsHeusler compoundElectronic Optical and Magnetic MaterialsCondensed Matter::Materials ScienceMagnetizationElectrical resistivity and conductivityengineeringAnisotropyPhysical Review B
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Time-of-flight photoelectron momentum microscopy with 80–500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter

2021

Journal of synchrotron radiation 28(6), 1891 - 1908 (2021). doi:10.1107/S1600577521010511

Nuclear and High Energy PhysicsSpectrum analyzerMaterials sciencePhotonMicroscopephotoelectron diffraction550Synchrotron radiationmomentum microscopylaw.inventionOpticslawddc:550Pulse waveTime domaintime of flight spectroscopy ; momentum microscopy ; ARPES ; photoelectron diffraction ; pulse pickingpulse pickingInstrumentationMomentum (technical analysis)Radiationbusiness.industryARPESResearch PapersTime of flighttime-of-flight spectroscopyPhysics::Accelerator Physicsbusiness
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CCDC 1434832: Experimental Crystal Structure Determination

2017

Related Article: A. Chernenkaya, A. Morherr, S. Backes, W. Popp, S. Witt, X. Kozina, S. A. Nepijko, M. Bolte, K. Medjanik, G. Öhrwall, C. Krellner, M. Baumgarten, H. J. Elmers, G. Schönhense, H. O. Jeschke, R. Valentí|2016|J.Chem.Phys.|145|034702|doi:10.1063/1.4958659

dithieno[23-d;2'3'-d']benzo[12-b;45-b']dithiophene tetracyanoquinodimethaneSpace GroupCrystallographyCrystal SystemCrystal StructureCell ParametersExperimental 3D Coordinates
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CCDC 1434834: Experimental Crystal Structure Determination

2017

Related Article: A. Chernenkaya, A. Morherr, S. Backes, W. Popp, S. Witt, X. Kozina, S. A. Nepijko, M. Bolte, K. Medjanik, G. Öhrwall, C. Krellner, M. Baumgarten, H. J. Elmers, G. Schönhense, H. O. Jeschke, R. Valentí|2016|J.Chem.Phys.|145|034702|doi:10.1063/1.4958659

Space GroupCrystallographyCrystal Systemdithieno[23-d;2'3'-d']benzo[12-b;45-b']dithiopheneCrystal StructureCell ParametersExperimental 3D Coordinates
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CCDC 1434833: Experimental Crystal Structure Determination

2017

Related Article: A. Chernenkaya, A. Morherr, S. Backes, W. Popp, S. Witt, X. Kozina, S. A. Nepijko, M. Bolte, K. Medjanik, G. Öhrwall, C. Krellner, M. Baumgarten, H. J. Elmers, G. Schönhense, H. O. Jeschke, R. Valentí|2016|J.Chem.Phys.|145|034702|doi:10.1063/1.4958659

Space GroupCrystallographyCrystal SystemCrystal StructureCell Parametersdithieno[23-d;2'3'-d']benzo[12-b;45-b']dithiophene tetrafluorotetracyanoquinodimethaneExperimental 3D Coordinates
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