Current Control of Spin Helicity and Nonreciprocal Charge Transport in a Multiferroic Conductor

Abstract

AbstractA multiferroic state with both electronic polarity (P) and magnetization (M) shows the inherently strong P‐M coupling when P is induced by cycloidal (Néel‐wall like) spin modulation. The sign of P is determined by the clockwise or counterclockwise rotation of spin, termed the spin helicity. Such a multiferroic state is not limited to magnetic insulators but can be broadly observed in conductors. Here, the current control of the multiferroics is reported in a helimagnetic metal YMn6Sn6 and its detection through nonreciprocal resistivity (NRR). The underlying concept is the coupling of the current with the toroidal moment as well as with the magneto‐chirality χv · M, where and χv are the unit modulation wave vector and the vector spin chirality, respectively. An enhancement of NRR is furthermore observed by the spin‐cluster scattering via χv and its fluctuation. These findings may pave the way to an exploration of multiferroic conductors and the application of the spin‐helicity degree of freedom as a state variable.