# Anomalous electrical magnetochiral effect by chiral spin fluctuation

## TL;DR

This paper theoretically demonstrates that vector spin chirality fluctuations in chiral magnets cause asymmetric electron scattering, leading to a significant electrical magnetochiral effect with potential for large nonreciprocal responses.

## Contribution

It reveals the microscopic mechanism by which vector spin chirality fluctuations induce nonreciprocal transport phenomena in conducting chiral magnets.

## Key findings

- eMChE depends on temperature and magnetic field as observed in MnSi
- Asymmetric scattering appears in the leading-order scattering term
- Results suggest potential for large nonreciprocal responses in chiral conductors

## Abstract

The non-collinear spin configurations cause many nontrivial phenomena related to the Berry phase. They are described by the vector spin chirality $\chi_{ij} ={\bf S}_i\times{\bf S}_j$ or scalar spin chirality $\chi_{ijk}=({\bf S}_i \times {\bf S}_j) \cdot {\bf S}_k$, which are related to the spin current and effective magnetic field, respectively. The scalar spin chirality leads to the topological Hall effect in metals, while the vector spin chirality to the ferroelectricity of spin origin, i.e., multiferroics in insulators. However, the role of the vector spin chirality in conducting systems has not yet elucidated. Here we show theoretically that the spin fluctuation with vector spin chirality in chiral magnets scatters electrons asymmetrically, resulting in a nonreciprocal transport phenomena, i.e., electrical magnetochiral effect (eMChE). This asymmetric scattering appears in the leading-order scattering term, implying a large nonreciprocity in the charge and spin currents. We find that the temperature and magnetic field dependence of the eMChE reproduces that observed in MnSi. Our results reveal the microscopic mechanism of eMChE and its potential in producing a large nonreciprocal response.