Monte Carlo Study of the Spin Transport in Magnetic Materials

TL;DR

This study uses extensive Monte Carlo simulations to analyze how spin transport resistivity in magnetic materials changes across phase transitions, confirming theoretical predictions and explaining the resistivity peak near critical points.

Contribution

The paper provides the first comprehensive Monte Carlo simulation of spin transport resistivity across magnetic phase transitions, validating theoretical models and explaining the resistivity peak.

Findings

Resistivity exhibits an anomalous peak at the magnetic transition.

The peak is due to magnetic domains in the critical region.

No resistivity peak observed in antiferromagnets.

Abstract

The resistivity in magnetic materials has been theoretically shown to depend on the spin-spin correlation function which in turn depends on the magnetic-field, the density of conduction electron, the magnetic ordering stability, etc. However, these theories involved a lot of approximations, so their validity remained to be confirmed. The purpose of this work is to show by extensive Monte Carlo (MC) simulation the resistivity of the spin current from low-$T$ ordered phase to high-$T$ paramagnetic phase in a ferromagnetic film. We take into account the interaction between the itinerant spins and the localized lattice spins as well as the interaction between itinerant spins themselves. We show that the resistivity undergoes an anomalous behavior at the magnetic phase transition in agreement with previous theories in spite of their numerous approximations. The origin of the resistivity peak near the phase transition in ferromagnets is interpreted here as stemming from the existence of magnetic domains in the critical region. This interpretation is shown to be in consistence with previous theoretical pictures. Resistivity in a simple cubic antiferromagnet is also shown. The absence of a peak in this case is explained.