Doping control of magnetism and emergent electromagnetic induction in high-temperature helimagnets

TL;DR

This study explores how doping in high-temperature helimagnets like YMn6Sn6 can control emergent electromagnetic induction, revealing new ways to optimize materials for room-temperature quantum inductors.

Contribution

It demonstrates how partial substitution of Y with Tb modulates the emergent inductance and its sign, expanding the potential for room-temperature emergent inductors.

Findings

Tb doping suppresses negative EEMI components

Positive EEMI persists in spin-collinear antiferromagnetic states

Thermally enhanced spin fluctuations contribute to EEMI

Abstract

Ac current-driven motions of spiral spin textures can give rise to emergent electric fields acting on conduction electrons. This in turn leads to the emergent electromagnetic induction effect which may realize quantum inductor elements of micrometer size. ${\rm YMn}_{6}{\rm Sn}_{6}$ is a helimagnet with a short helical period (2-3 nm) that shows this type of emergent inductance beyond room temperature. To identify the optimized materials conditions for ${\rm YMn}_{6}{\rm Sn}_{6}$-type room-temperature emergent inductors, we have investigated emergent electromagnetic inductance (EEMI) as the magnetism is modified through systematic partial substitution of Y by Tb. By small angle neutron scattering and inductance measurements, we have revealed that the pinning effect on the spin-helix translational mode by Tb doping selectively and largely suppresses the negative component of EEMI, while sustaining the positive inductance arising from the spin tilting mode. We also find that in addition to the spin helix, even the spin-collinear antiferromagnetic structure can host the positive EEMI due to thermally enhanced spin fluctuations. The present study highlights the facile control of both the magnitude and sign of EEMI beyond room temperature, and thus suggests a route to expand the range of emergent inductor candidate materials.