Search results for "Magnetization"
showing 10 items of 550 documents
The Properties of Co2Cr1-xFexAl Heusler Compounds
2006
The classical concept of band structure tuning as used for semiconductors by partly replacing one atom by a chemical neighbor without altering the structure is applied examplarily to the half-metallic ferromagnetic Heusler compound Co 2 Cr 1 - x Fe x Al. Band structure calculations are presented for ordered and disordered compounds. We present experimental and theoretical results. The connection between specific site disorder and the band structure is shown explicitly with particular emphasis on the half-metallic properties. Experimentally observed deviations from the ideal Heusler structure and from the simple Slater-Pauling rule for the magnetization are discussed in close relation to the…
Magnetic interface formation at Fe/Cr/Fe(100)
1997
Photoemission magnetic dichroism of Fe and Cr 3p core levels was employed to investigate the magnetic order at the Fe/Cr/Fe(100) interface. For submonolayer and monolayer Fe coverages on Cr(100) the interface system appears magnetically frustrated, with no net magnetization along the parallel (antiparallel) direction of the substrate magnetization. The analysis of the Fe 3p photoemission dichroism allows to conclude that, at these low coverages, Fe is magnetically ordered but along an axis lying at 90° from the substrate Fe(100) magnetization, favoring the interpretation of biquadratic coupling between the ultrathin iron overlayer and the bulk iron substrate, across the Cr interlayer.
How Lasers Can Help Probe the Distribution of Nuclear Magnetism
1989
Publisher Summary High-resolution atomic spectroscopy has played an important part in the study of nuclear electric and magnetic structure. Laser spectroscopy has been crucial for the measurement of isotope shifts, which reflect the variations of nuclear charge radii and shapes. High sensitivity and frequency resolution have allowed experiments to be carried out systematically over extensive ranges of stable and radioactive isotopes with lifetime as short as a few milliseconds. While the laser experiments also yield results for nuclear multipole moments, no measurements are obtained of the distribution of nuclear magnetization. Nuclear structure properties can be probed by penetrating elect…
Accidentally on purpose: construction of a ferromagnetic, oxime-based [MnIII2] dimer
2011
The serendipitous self-assembly of the complex [Mn(III)(2)Zn(II)(2)(Ph-sao)(2)(Ph-saoH)(4)(hmp)(2)] (1),whose magnetic core consists solely of two symmetry equivalent Mn(iii) ions linked by two symmetry equivalent -N-O- moieties, provides a relatively simple model complex with which to study the magneto-structural relationship in oxime-bridged Mn(III) cluster compounds. Dc magnetic susceptibility measurements reveal ferromagnetic (J = +2.2 cm(-1)) exchange resulting in an S = 4 ground state. Magnetisation measurements performed at low temperatures and high fields reveal the presence of significant anisotropy, with ac measurements confirming slow relaxation of the magnetisation and Single-Mo…
The Missing Link in the Magnetism of Hybrid Cobalt Layered Hydroxides: The Odd‐Even Effect of the Organic Spacer
2021
A dramatic change in the magnetic behaviour, which solely depends on the parity of the organic linker molecules, has been found in a family of layered CoII hydroxides covalently functionalized with dicarboxylic molecules. These layered hybrid materials have been synthesized at room temperature using a one-pot procedure through the epoxide route. While hybrids connected by odd alkyl chains exhibit coercive fields (Hc) below ca. 3500 Oe and show spontaneous magnetization at temperatures (TM) below 20 K, hybrids functionalized with even alkyl chains behave as hard magnets with Hc>5500 Oe and display a TM higher than 55 K. This intriguing behaviour was studied by density functional theory with …
Impact of local order and stoichiometry on the ultrafast magnetization dynamics of Heusler compounds
2015
Nowadays, a wealth of information on ultrafast magnetization dynamics of thin ferromagnetic films exists in the literature. Information is, however, scarce on bulk single crystals, which may be especially important for the case of multi-sublattice systems. In Heusler compounds, representing prominent examples for such multi-sublattice systems, off-stoichiometry and degree of order can significantly change the magnetic properties of thin films, while bulk single crystals may be generally produced with a much more well-defined stoichiometry and a higher degree of ordering. A careful characterization of the local structure of thin films versus bulk single crystals combined with ultrafast demag…
Magnetic states in low-pinning high-anisotropy material nanostructures suitable for dynamic imaging
2013
We present magnetic domain states in a material configuration with high (perpendicular) magnetic anisotropy and particularly low magnetic pinning. This material, a B-doped Co/Pt multilayer configuration, exhibits a strong magnetic contrast in x-ray transmission experiments, making it apt for dynamic imaging with modern synchrotron techniques, providing high spatial and high temporal resolution simultaneously. By analyzing the static spin structures in nanodisks at variable external fields, we show that CoB/Pt multilayers exhibit low enough domain wall pinning to manipulate the domain pattern with weak stimuli and in particular to move domains and domain walls. We demonstrate in a proof-of-p…
Nonequilibrium magnetization dynamics of gadolinium studied by magnetic linear dichroism in time-resolved 4f core-level photoemission.
2008
The magnetic linear dichroism of the gadolinium 4f core level is studied in a time-resolved photoemission experiment employing laser pump- and synchrotron-radiation probe pulses. Upon optical excitation of the 5d6s valence electrons with femtosecond laser pulses, the magnetic order in the 4f spin system is reduced. Remarkably, the linear dichroism remains at 80% of the equilibrium contrast while the lattice temperature reaches the Curie temperature due to electron-phonon scattering. Contrasting itinerant ferromagnets, this shows that equilibration between the lattice and spin subsystems takes in Gd about 80 ps and is established in parallel with heat diffusion.
Magnetic state control via field-angle-selective switching in asymmetric rings
2020
Switching the chirality of the vortex state in asymmetric ferromagnetic rings is interesting for multistate memory devices, logic elements, and stray-field-based rotation sensors. This study shows that different magnetic states can be configured by carefully tuning the magnetic field angle. Using time-resolved scanning electron microscopy with polarization analysis to image the magnetization dynamics of these rings, the authors detect competing switching pathways for certain field angles. These different pathways do not change the resulting magnetic states, though, which is advantageous for engineering reliable devices for a range of potential spintronic applications.
Investigating spintronics thin film systems with synchrotron radiation
2009
Abstract Spintronics is a research field involving a wide variety of different magnetic materials. Synchrotron radiation in the VUV and soft X-ray regime is ideally suited to investigate the relationships between magnetic properties and electronic structure of spintronics thin film stacks. Complex layered structures and nanomagnets are the main building blocks for current and future spintronics applications. In this contribution we describe the study of spintronics model systems with respect to the static and dynamic behavior with an emphasis on interfaces.