Electrical magnetochiral effect induced by chiral spin fluctuations in MnSi

Chirality of matter can give rise to unique responses in optics, electricity and magnetism. One such example is electrical magnetochiral effect (eMChE), which is directional nonlinear magnetotransport in proportion to an inner-product of B and j [1,2]. Electrical magnetochiral effect in magnetic materials has not been reported so far.
We investigate eMChE in a prototype chiral helimagnet of MnSi. Prominent electrical magnetochiral signals emerge at specific temperature-magnetic field-pressure regions: in the paramagnetic phase just above the helical ordering temperature and in the partially-ordered topological spin state at low temperatures and high pressures, where thermal and quantum spin fluctuations are conspicuous in proximity of classical and quantum phase transitions, respectively. The results indicate that eMChE in MnSi is related to spin fluctuations endowed with a finite spin chirality, which induce asymmetric electron scatterings.
[1] G. L. J. A. Rikken et al., Phys Rev. Lett. 87, 236602 (2001).
[2] F. Pop et al., Nat. Commun. 5, 3757 (2014).