Yamaguchi Daiki, Kitaori Aki, Nagaosa Naoto, Tokura Yoshinori
Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan.
RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.
Adv Mater. 2025 May;37(20):e2420614. doi: 10.1002/adma.202420614. Epub 2025 Apr 7.
A 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 YMnSn 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 χ · M, where and χ 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 χ 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.
当电子极化（P）由摆线（类奈尔壁）自旋调制诱导产生时，同时具有电子极化（P）和磁化强度（M）的多铁性态呈现出固有的强P-M耦合。P的符号由自旋的顺时针或逆时针旋转决定，这被称为自旋螺旋性。这种多铁性态不仅限于磁性绝缘体，在导体中也能广泛观察到。在此，报道了在螺旋磁性金属YMnSn中对多铁性体的电流控制及其通过非互易电阻率（NRR）的检测。其基本概念是电流与环形矩以及与磁手征性χ·M的耦合，其中 和χ分别是单位调制波矢和矢量自旋手征性。此外，通过χ及其涨落的自旋团簇散射观察到NRR增强。这些发现可能为探索多铁性导体以及将自旋螺旋性自由度作为一个状态变量的应用铺平道路。
