Search results for "Magnetic structure"
showing 10 items of 40 documents
Spin Hall magnetoresistance in the non-collinear ferrimagnet GdIG close to the compensation temperature
2017
We investigate the spin Hall magnetoresistance (SMR) in a gadolinium iron garnet (GdIG)/platinum (Pt) heterostructure by angular dependent magnetoresistance measurements. The magnetic structure of the ferromagnetic insulator GdIG is non-collinear near the compensation temperature, while it is collinear far from the compensation temperature. In the collinear regime, the SMR signal in GdIG is consistent with the usual [Formula: see text] relation well established in the collinear magnet yttrium iron garnet, with [Formula: see text] the angle between magnetization and spin Hall spin polarization direction. In the non-collinear regime, both an SMR signal with inverted sign and a more complex an…
The phase diagram and the magnetic structure of nuclear spins in elemental copper below 60 nK
1992
Abstract The phase diagram for nuclear magnetic order is elemental copper and the corresponding ordering vectors were investigated by neutron diffraction at nanokelvin temperatures. The intermediate phase is characterized by an ordering vector (O 2 3 2/3 . This is the first time that this type of order is observed in an fcc antiferromagnet.
Development of a scanning electron microscopy with polarization analysis system for magnetic imaging with ns time resolution and phase-sensitive dete…
2018
Scanning electron microscopy with polarization analysis is a powerful lab-based magnetic imaging technique offering simultaneous imaging of multiple magnetization components and a very high spatial resolution. However, one drawback of the technique is the long required acquisition time resulting from the low inherent efficiency of spin detection, which has limited the applicability of the technique to certain quasi-static measurement schemes and materials with high magnetic contrast. Here we demonstrate the ability to improve the signal-to-noise ratio for particular classes of measurements involving periodic excitation of the magnetic structure via the implementation of a digital phase-sens…
Surface magnetic structure investigation of a nanolaminated Mn$_2$GaC thin film using a magnetic field microscope based on Nitrogen-Vacancy centers
2021
This work presents a magnetic field imaging method based on color centers in diamond crystal applied to a thin film of a nanolaminated Mn$_2$GaC MAX phase. Magnetic properties of the surface related structures have been described around the first order transition at 214 K by performing measurements in the temperature range between 200 K and 235 K with the surface features fading out by increasing temperature above the transition temperature. The results presented here demonstrate how Nitrogen-Vacancy center based magnetic microscopy can supplement the traditionally used set of experimental techniques, giving additional information of microscopic scale magnetic field features, and allowing t…
Domain Wall Spin Structures in Mesoscopic Fe Rings probed by High Resolution SEMPA
2016
We present a combined theoretical and experimental study of the energetic stability and accessibility of different domain wall spin configurations in mesoscopic magnetic iron rings. The evolution is investigated as a function of the width and thickness in a regime of relevance to devices, while Fe is chosen as a material due to its simple growth in combination with attractive magnetic properties including high saturation magnetization and low intrinsic anisotropy. Micromagnetic simulations are performed to predict the lowest energy states of the domain walls, which can be either the transverse or vortex wall spin structure, in good agreement with analytical models, with further simulations …
Magnetic properties of GdPdSb and GdNiSb studied by 155Gd-Mössbauer spectroscopy
2009
Abstract 155 Gd-Mossbauer spectroscopy was applied to study the magnetic properties of GdPdSb with hexagonal LiGaGe structure and of GdNiSb in the cubic MgAgAs-type structure as well as in the hexagonal AlB 2 -type structure. In GdPdSb magnetic ordering is observed at 13.0 K with indications of a tilted spin structure at lower temperatures. In the cubic phase of GdNiSb magnetic ordering is observed at 9.5 K and in the hexagonal phase around 3.5 K. These results are discussed in conjunction with previous investigations of these samples.
The Role of Order-Disorder Transitions in the Quest for Molecular Multiferroics: Structural and Magnetic Neutron Studies of a Mixed Valence Iron (II)…
2012
Neutron diffraction studies have been carried out to shed light on the unprecedented order-disorder phase transition (ca. 155 K) observed in the mixed-valence iron(II)-iron(III) formate framework compound [NH 2(CH3)2]n[FeIIIFe II(HCOO)6]n. The crystal structure at 220 K was first determined from Laue diffraction data, then a second refinement at 175 K and the crystal structure determination in the low temperature phase at 45 K were done with data from the monochromatic high resolution single crystal diffractometer D19. The 45 K nuclear structure reveals that the phase transition is associated with the order-disorder of the dimethylammonium counterion that is weakly anchored in the cavities …
Electronic structure of the austenitic and martensitic state of magnetocaloric Ni-Mn-In Heusler alloy films
2013
Changes of the electronic and magnetic structure near the martensitic phase transition of Ni-Mn-In Heusler alloys doped with Co are investigated by experiment and theory. The nonstoichiometric Ni${}_{48}$Co${}_{5}$Mn${}_{35}$In${}_{12}$ epitaxial film undergoes a transition from a weakly magnetic martensitic phase below ${T}_{m}=350$ K to a ferromagnetic austenitic phase above ${T}_{m}$. Element-specific magnetic moments and the unoccupied density of states function is investigated using x-ray magnetic circular dichroism. We find an antiparallel alignment of Mn and Ni/Co magnetic moments in both phases. The electronic structure is calculated using the SPR-KKR Green's function approach consi…
Laser-induced torques in spin spirals
2020
We investigate laser-induced torques in magnetically non-collinear ferromagnets with a spin-spiral magnetic structure using \textit{ab-initio} calculations. Since spin-spirals may be used to approximate the magnetization gradients locally in domain walls and skyrmions, our method may be used to obtain the laser-induced torques in such objects from a multiscale approach. Employing the generalized Bloch-theorem we obtain the electronic structure computationally efficiently. We employ our method to assess the laser-induced torques in bcc Fe, hcp Co, and L$_{1}0$ FePt when a spin-spiral magnetic structure is imposed. We find that the laser-induced torques in these magnetically noncollinear syst…
Diffusive thermal dynamics for the spin-S Ising ferromagnet
2008
We introduce an alternative thermal diffusive dynamics for the spin-S Ising ferromagnet realized by means of a random walker. The latter hops across the sites of the lattice and flips the relevant spins according to a probability depending on both the local magnetic arrangement and the temperature. The random walker, intended to model a diffusing excitation, interacts with the lattice so that it is biased towards those sites where it can achieve an energy gain. In order to adapt our algorithm to systems made up of arbitrary spins, some non trivial generalizations are implied. In particular, we will apply the new dynamics to two-dimensional spin-1/2 and spin-1 systems analyzing their relaxat…