arXiv subjects

Kazushige Hyodo

Publications and source records attributed to Kazushige Hyodo.

3 recordsLinked to original sources

arXiv2017

First-principles study on the magnetic properties of ordered Nd$_{6}$(Fe,Ga)$_{14}$ alloys

We studied the stable magnetic structure of ordered Nd$_{6}$Fe$_{14-x}$Ga$_x$ ($x = 0, 1)$ alloys, which appears in the grain-boundary (GB) phase of Nd-Fe-B permanent magnets, using first-principles techniques. Slight Ga doping ($x = 1$) was shown to contribute to the stabilization of an anti-ferromagnetic (AF) state, whereas the non-doped case ($x = 0$) was revealed to favor ferromagnetic state rather than AF state with a slight energy difference.

cond-mat.mtrl-sci↗

arXiv2016

Effects of spin fluctuation on the magnetic anisotropy constant of itinerant electron magnets

In the disordered local moment picture, we calculated the magnetization (M) and magnetic anisotropy energy (MAE) of FePt, CoPt, and MnAl ordered alloys and body-centered tegragonal FeCo (bct-FeCo) disordered alloy, assuming spatially fluctuated spin configurations at finite temperatures. All alloys exhibit the relation K1(T)/K1(0)=(M(T)/M(0))^n with the exponent (n) around 2. This is consistent with the two-ion anisotropy model, in contrast to the usual single-ion anisotropy model exhibiting n=3. Because these systems have different mechanisms of MAE, we suggest that this relation is a general rule for itinerant electron systems.

cond-mat.mtrl-sci↗

arXiv2012

Effect of Spin Torque on Magnetization Switching Speed Having Nonuniform Spin Distribution

We study the influence of the spin torque, which depends on the space and time derivative of magnetization, on magnetization reversal time in a ferromagnetic fine particle. The spin torque operates to dissipate the angular momentum of the magnetization precession, and the torque increases in a spin vortex structure. We calculate the magnetization reversal time under a DC magnetic field using the Landau-Lifshitz-Gilbert equation containing a spin torque term. We found that the spin torque changes the magnetization switching speed significantly during the reversal process by maintaining a spin vortex in an intermediate state.

cond-mat.mes-hall↗