Universal Ratio of Intrinsic Resistivities of Spin Helix in B20 (Fe-Co)Si Magnets

TL;DR

This study measures the intrinsic resistivity of spin helices in B20 (Fe-Co)Si magnets, revealing a universal resistance ratio influenced by strong spin-orbit coupling, distinct from traditional ferromagnets.

Contribution

It reports the first measurement of a universal resistance ratio in B20 magnets' spin helices, highlighting the impact of spin-orbit coupling on resistivity.

Findings

Universal resistance ratio gamma = 1.35 independent of composition and temperature.

Gamma is significantly smaller than the 3 value in traditional ferromagnets.

Strong spin-orbit coupling reduces domain wall resistivity in B20 magnets.

Abstract

The B20 magnets with the Dzyaloshinskii-Moriya (D-M) interaction exhibit spin helix and Skyrmion spin textures unattainable in traditional Heisenberg ferromagnets. We have determined the intrinsic resistivity of the spin helix, which is a macroscopic Bloch domain wall, in B20 (Fe-Co)Si magnets. We found a universal resistance ratio of gamma = 1.35 with current parallel and perpendicular to the helix, independent of composition and temperature. This gamma value is much smaller than 3, the well-known minimum value for domain wall resistivity in traditional ferromagnets, due to the significant spin-orbit coupling in the B20 magnets.