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The finite-temperature magnetic properties of ${\text{Fe}}_{x}{\text{Pd}}_{1\ensuremath{-}x}$ and ${\text{Co}}_{x}{\text{Pt}}_{1\ensuremath{-}x}$ alloys have been investigated. It is shown that the temperature-dependent magnetic behavior of these alloys cannot be described properly unless the coupling between the magnetic moments at the Fe and Co mediated through the interactions with the induced magnetic moments of the nonmagnetic Pd and Pt atoms is included. A scheme for the calculation of the Curie temperature $({T}_{C})$ for this type of systems is presented that is based on the extended Heisenberg Hamiltonian with the appropriate exchange parameters ${J}_{ij}$ obtained from ab initio electronic-structure calculations. Within the present study the Korringa-Kohn-Rostoker Green's-function method has been used to calculate the ${J}_{ij}$ parameters. The Curie temperatures obtained for ${\text{Fe}}_{x}{\text{Pd}}_{1\ensuremath{-}x}$ and ${\text{Co}}_{x}{\text{Pt}}_{1\ensuremath{-}x}$ alloys are compared with the corresponding experimental data. The experimental results for ${\text{Fe}}_{x}{\text{Pd}}_{1\ensuremath{-}x}$ alloys have been obtained within anomalous Hall-effect measurements. The agreement between theoretical results and all available experimental data is rather good.

The exchange stiffness constants of chemically disordered ${\text{Fe}}_{x}{\text{Pt}}_{1\ensuremath{-}x}$ films with thickness around 50 nm were determined by means of ferromagnetic resonance. It was found to increase with increasing Fe content from $6\ifmmode\pm\else\textpm\fi{}4\text{ }\text{pJ}/\text{m}$ for $x=0.27$ to $15\ifmmode\pm\else\textpm\fi{}4\text{ }\text{pJ}/\text{m}$ for $x=0.67$. Theoretical results from fully relativistic and scalar-relativistic band-structure calculations using the Korringa-Kohn-Rostoker method confirm the experimentally obtained values. In addition, determination of the magnetocrystalline anisotropy by angular-dependent measurements of the ferromagnetic resonance gave the possibility to estimate the exchange length that was found to be 40--50 nm for all compositions investigated in this work.

The influence of the spin-orbit coupling on the magnetic structure of deposited transition-metal nanostructures has been studied by fully relativistic electronic-structure calculations. The interplay of exchange coupling and magnetic anisotropy was monitored by studying the corresponding magnetic torque calculated within ab initio and model approaches. We find that a spin-orbit-induced Dzyaloshinski-Moriya interaction has a profound effect on the spin structure of such complex magnetic systems and that in combination with magnetic anisotropies and isotropic exchange this can result in peculiar magnetic properties.

The complex correlation of structure and magnetism in highly coercive monoatomic FePt surface alloys is studied using scanning tunneling microscopy, x-ray magnetic circular dichroism, and ab initio theory. Depending on the specific lateral atomic coordination of Fe either hard magnetic properties comparable to that of bulk FePt or complex noncollinear magnetism due to Dzyaloshinski-Moriya interactions are observed. Our calculations confirm the subtle dependence of the magnetic anisotropy and spin alignment on the local coordination and suggest that 3D stacking of Fe and Pt layers in bulk $L{1}_{0}$ magnets is not essential to achieve high-anisotropy values.

A different scheme to calculate the exchange tensor ${\underset{}{J}}_{ij}$ describing in a phenomenological way the anisotropic exchange coupling of two moments in a magnetically ordered system is presented. The ab initio approach is based on spin-polarized relativistic multiple-scattering theory within the framework of spin-density functional theory. The scheme is applied to ferromagnetic CrTe as well as the diluted magnetic semiconductor system ${\text{Ga}}_{1\ensuremath{-}x}{\text{Mn}}_{x}\text{As}$. In the latter case the results show that there is a noticeable anisotropy in the exchange coupling present, although not as pronounced as those suggested in recent theoretical investigations.

Systematic trends in the magnetism of Co-Pt solid-state systems are explored by studying the effects of composition, electron correlations, spin-orbit coupling (SOC), and long-range order. Ab initio fully relativistic calculations were performed for bulk Co, a substitutional Pt impurity in Co, ${\text{Co}}_{3}\text{Pt}$, CoPt, ${\text{CoPt}}_{3}$, and a substitutional Co impurity in Pt. Many-body effects beyond the local spin-density approximation (LSDA) were included via the dynamical mean-field theory (DMFT); a comparison with results based on the Brooks orbital-polarization (OP) scheme was also made. The disorder was treated within the coherent-potential approximation. We found that while the spin magnetic moments ${\ensuremath{\mu}}_{\text{spin}}$ at the Co atoms monotonously increase with increasing Pt concentration, the orbital magnetic moments ${\ensuremath{\mu}}_{\text{orb}}$ do not follow the trend of ${\ensuremath{\mu}}_{\text{spin}}$. Magnetic moments ${\ensuremath{\mu}}_{\text{spin}}$ and ${\ensuremath{\mu}}_{\text{orb}}$ at Pt atoms do not depend on Pt concentration monotonously. Most of these trends can be understood in terms of hybridization and site-dependent SOC. The OP scheme of Brooks corrects the deficiencies of a pure LSDA only if the Pt concentration is low. The $\text{LSDA}+\text{DMFT}$ scheme provides ${\ensuremath{\mu}}_{\text{orb}}/{\ensuremath{\mu}}_{\text{spin}}$ ratios for Co atoms which agree with experiment even for high Pt content. Introducing disorder leads to an enhancement of ${\ensuremath{\mu}}_{\text{spin}}$ at Co atoms and to a suppression of ${\ensuremath{\mu}}_{\text{spin}}$ at Pt atoms. The ${\ensuremath{\mu}}_{\text{orb}}$ at Co atoms does not exhibit any systematic dependence on the degree of order, while ${\ensuremath{\mu}}_{\text{orb}}$ at Pt atoms decreases with increasing disorder for all Pt concentrations.

The room temperature intercalation of Cr2Ti3Se8 with butyl lithium yields a phase mixture of the starting material and of the new trigonal phase with composition Li0.4Cr0.5Ti0.75Se2. The phase pure fully intercalated trigonal phase is obtained at elevated temperature (80 degrees C) with the final composition Li0.62Cr0.5Ti0.75Se2. The line profile analysis (LPA) of the powder patterns shows that pronounced strain occurs in the intercalated material. The deintercalation of the material is realized by treatment of the fully intercalated sample with distilled water leading to the composition Li0.15Cr0.5Ti0.75Se2. The intercalation is accompanied by an electron transfer from the guest Li to the host material, and as a consequence significant changes of the interatomic distances are observed. The local environment and the dynamics of the Li+ ions in the fully intercalated sample were studied with 7Li magic angle spinning (MAS) NMR investigations. These reveal different environments of transition metal neighbors for the Li sites and a high mobility of the Li ions. Magnetic measurements show that in the pristine material antiferromagnetic interactions are dominating (theta = -113.5 K) with no long-range order at low temperatures. The magnetic ground state is characterized by a spin-glass behavior. With increasing Li content the antiferromagnetic character vanishes progressively, and the fully intercalated phase exhibits a positive Weiss constant (theta = 12 K) indicating dominating ferromagnetic exchange interactions; i.e., the magnetic properties can be significantly altered by lithiation. The interpretation of our experimental findings is supported by the results of accompanying band structure calculations done within the framework of local spin density functional theory. These demonstrate in particular the role of the charge transfer between the constituents as a function of the Li concentration and its impact on the exchange coupling.

The central goals of nanoscale magnetic materials science are the self-assembly of the smallest structure exhibiting ferromagnetic hysteresis at room temperature, and the assembly of these structures into the highest density patterns. The focus has been on chemically ordered alloys combining magnetic 3d elements with polarizable 5d elements having high spin–orbit coupling and thus yielding the desired large magneto-crystalline anisotropy. The chemical synthesis of nanoparticles of these alloys yields disordered phases requiring annealing to transform them to the high-anisotropy L10 structure. Despite considerable efforts, so far only part of the nanoparticles can be transformed without coalescence. Here we present an alternative approach to homogeneous alloys, namely the creation of nanostructures with atomically sharp bimetallic interfaces and interlines. They exhibit unexpectedly high magnetization reversal energy with values and directions of the easy magnetization axes strongly depending on chemistry and texture. We find significant deviations from the expected behaviour for commonly used element combinations. Ab-initio calculations reproduce these results and unravel their origin., The design and assembly of nanostructures exhibiting ferromagnetic hysteresis at room temperature are recognized goals for high-density data storage. Here, the authors engineer nanostructures with atomically sharp bimetallic interfaces and interlines, which exhibit large magnetic anisotropy and high temperature hysteresis.

The structural and magnetic properties of CrSb compounds with NiAs structure have been studied by means of the Korringa-Kohn-Rostoker (KKR) band structure method. An analysis of the structural and magnetic stability has been performed on the basis of total energy calculations for various magnetic states. The magnetic properties at finite temperature have been investigated by means of Monte Carlo simulations on the basis of a classical Heisenberg Hamiltonian and the exchange coupling parameters calculated from first principles. This approach allowed us to determine the critical temperature in good agreement with experiment.

A Kubo-Greenwood-like equation for the Gilbert damping parameter $\alpha$ is presented that is based on the linear response formalism. Its implementation using the fully relativistic Korringa-Kohn-Rostoker (KKR) band structure method in combination with Coherent Potential Approximation (CPA) alloy theory allows it to be applied to a wide range of situations. This is demonstrated with results obtained for the bcc alloy system Fe$_x$Co$_{1-x}$ as well as for a series of alloys of permalloy with 5d transition metals. To account for the thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. The corresponding calculations for Ni correctly describe the rapid change of $\alpha$ when small amounts of substitutional Cu are introduced.

Recently, the interplay between spin and lattice degrees of freedom has gained a lot of attention due to its importance for various fundamental phenomena as well as for spintronic and magnonic applications. Examples are ultrafast angular momentum transfer between the spin and lattice subsystems during ultrafast demagnetization, frustration driven by structural distortions in transition-metal oxides, or in acoustically driven spin-wave resonances. In this work, we provide a systematic analysis of spin-lattice interactions for ferro- and antiferromagnetic materials and focus on the role of lattice symmetries and dimensions, magnetic order, and the relevance of spin-lattice interactions for angular momentum transfer as well as magnetic frustration. For this purpose, we use a recently developed scheme, which allows an efficient calculation of spin-lattice interaction tensors from first principles. In addition to that, we provide a more accurate and self-consistent scheme to calculate ab initio spin-lattice interactions by using embedded clusters, which allows us to benchmark the performance of the scheme introduced previously. published