Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan.
RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.
Nat Commun. 2017 Oct 11;8(1):866. doi: 10.1038/s41467-017-01094-2.
Chirality of matter can produce unique responses in optics, electricity and magnetism. In particular, magnetic crystals transmit their handedness to the magnetism via antisymmetric exchange interaction of relativistic origin, producing helical spin orders as well as their fluctuations. Here we report for a chiral magnet MnSi that chiral spin fluctuations manifest themselves in the electrical magnetochiral effect, i.e. the nonreciprocal and nonlinear response characterized by the electrical resistance depending on inner product of current and magnetic field. 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 finding of the asymmetric electron scattering by chiral spin fluctuations may explore new electromagnetic functionality in chiral magnets.The magnetism-induced chirality in electron transportation is of fundamental importantance in condensed matter physics but the origin is still unclear. Here the authors demonstrate that the asymmetric electron scattering by chiral spin fluctuations can be the key to the electrical magnetochiral effect in MnSi.
物质的手性可以在光学、电学和磁学中产生独特的响应。特别是，磁性晶体通过相对论起源的反称交换相互作用将其手性传递给磁性，从而产生螺旋自旋有序及其涨落。在这里，我们报告了手性磁体 MnSi 的情况，手性自旋涨落表现为电磁手性效应，即电阻取决于电流和磁场的内积的非互易和非线性响应。在特定的温度-磁场-压力区域会出现突出的电磁手性信号：在螺旋有序温度以上的顺磁相中和在低温和高压下的部分有序拓扑自旋相中，在接近经典和量子相变处，热和量子自旋涨落分别明显。手性自旋涨落引起的不对称电子散射的发现可能会在手性磁体中探索新的电磁功能。在凝聚态物理中，电子输运中的磁致手性具有重要的基础性意义，但起源仍不清楚。在这里，作者证明了手性自旋涨落引起的不对称电子散射可能是 MnSi 中电磁手性效应的关键。
