Formation of a topological non-Fermi liquid in MnSi
Formation of a topological non-Fermi liquid in MnSi
复制标题
DOI：
10.1038/nature12023
复制
发表时间：
2013-05-09
期刊：
影响因子：
64.8
通讯作者：
Pfleiderer, C.
中科院分区：
文献类型：
--
作者：
Ritz, R.;Halder, M.;Pfleiderer, C.
费米液体理论为描述金属中的传导电子及其有序现象（例如超导性、铁磁性以及自旋和电荷密度波有序）提供了一个非常强大的框架。令人感兴趣的另一类有序现象涉及受拓扑保护的自旋构型，也就是说，只有通过迫使局部平均磁化强度为零（1）才能破坏它们的拓扑。这种配置的例子有刺猬（所有自旋都指向内或向外的点）和涡旋。一个中心问题涉及在存在这种拓扑上不同的自旋纹理的情况下金属态的性质。在这里，我们报告了对 MnSi 中斯格明子晶格边界金属态的高压研究，它代表了一种由拓扑非平凡涡旋组成的新形式的磁序(2)。当长程磁序在压力下受到抑制时，斯格明子晶格的关键特性——即由于与拓扑绕组相关的涌现磁通量而产生的拓扑霍尔信号——在符号或大小上不受影响，并成为金属态的重要特性。因此，温度、压力和磁场中的拓扑霍尔信号的范围与显着的非费米液体电阻率的异常扩展的范围一致(3,30)。在 NFL 电阻率范围内对拓扑霍尔信号的观察表明，自旋与非平凡拓扑特征的相关性可能会导致纯金属中费米液体理论的崩溃。
Fermi liquid theory provides a remarkably powerful framework for the description of the conduction electrons in metals and their ordering phenomena, such as superconductivity, ferromagnetism, and spin-and charge-density-wave order. A different class of ordering phenomena of great interest concerns spin configurations that are topologically protected, that is, their topology can be destroyed only by forcing the average magnetization locally to zero(1). Examples of such configurations are hedgehogs (points at which all spins are either pointing inwards or outwards) and vortices. A central question concerns the nature of the metallic state in the presence of such topologically distinct spin textures. Here we report a high-pressure study of the metallic state at the border of the skyrmion lattice in MnSi, which represents a new form of magnetic order composed of topologically non-trivial vortices(2). When long-range magnetic order is suppressed under pressure, the key characteristic of the skyrmion lattice-that is, the topological Hall signal due to the emergent magnetic flux associated with the topological winding-is unaffected in sign or magnitude and becomes an important characteristic of the metallic state. The regime of the topological Hall signal in temperature, pressure and magnetic field coincides thereby with the exceptionally extended regime of a pronounced non-Fermi-liquid resistivity(3,30). The observation of this topological Hall signal in the regime of the NFL resistivity suggests empirically that spin correlations with non-trivial topological character may drive a breakdown of Fermi liquid theory in pure metals.