Spin-Fluctuation Mechanism of Anomalous Temperature Dependence of Magnetocrystalline Anisotropy in Itinerant Magnets

Abstract

The origins of the anomalous temperature dependence of magnetocrystalline anisotropy in (Fe1−xCox)2B alloys are elucidated using first-principles calculations within the disordered local moment model. Excellent agreement with experimental data is obtained. The anomalies are associated with the changes in band occupations due to Stoner-like band shifts and with the selective suppression of spin-orbit "hot spots" by thermal spin fluctuations. Under certain conditions, the anisotropy can increase, rather than decrease, with decreasing magnetization due to these peculiar electronic mechanisms, which contrast starkly with those assumed in existing models.

Tunable dimensional crossover and magnetocrystalline anisotropy in Fe2P -based alloys

“…these alloys. This agreement suggests that the MCA energy in Fe 2 P is not dominated by spin-orbit "hot spots," which would be strongly suppressed by disorder [20]. Further, we see that the behavior of K is primarily controlled by band filling.…”

“…To find this maximum, we calculate K(0,x) in CPA and approximate the temperature dependence as follows. It is often possible to calculate K(T ) using the disordered local moment method [20,34], but we do not have a quantitative model to represent the statistical distribution of the magnetic moments and their orientations in the present system with a weakly magnetic sublattice and a dimensional crossover. Therefore, we turn to the experimental data on K(T ), which were measured at several concentrations in Ni-doped Fe 2 P [10,11].…”

“…Substitutional disorder was treated using our implementation of the coherent potential approximation (CPA) [17] with spin-orbit coupling (SOC) included and the MCA energy K calculated following Refs. [18][19][20]. The atomic sphere radii were carefully chosen to reproduce the full-potential band structure.…”

Giant magnetic anisotropy of heavyp-elements on high-symmetry substrates: a new paradigm for supported nanostructures

“…Note that in a certain surface ligand field, the splitting of degenerate orbitals under a SOI could also take place for adatom/dimer with d or f orbitals. And this effect in d systems have been reported early [68][69][70][71]. However, the fresh material in p electrons is that for p electron systems, p z is the only orbital which is out-of-plane, so it is possible to tune this orbital separately without bringing a strong influence on the other orbitals.…”

A Landau‐Lifshitz‐Gilbert‐Type equation and torsion effects on the dynamics of magnetization

“…In this form, it is possible to study the transport phenomena . Overlapping between electronic wave functions are well‐understood interactions, again thanks to Quantum Mechanics; however, there are other kinds of interactions occurring such as magnetocrystalline anisotropy, connected with the temperature dependence and demagnetization fields , acting in a short range. In such systems, if we only consider the precession, we do not reach the right limit.…”