Quantum impurity in a nearly critical two-dimensional antiferromagnet
Quantum impurity in a nearly critical two-dimensional antiferromagnet
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近乎临界的二维反铁磁体中的量子杂质
DOI：
10.1126/science.286.5449.2479
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发表时间：
1999
期刊：
影响因子：
56.9
通讯作者：
M. Vojta
中科院分区：
文献类型：
--
作者：
S. Sachdev;C. Buragohain;M. Vojta
本文描述了二维绝缘反铁磁体中任意定域杂质的自旋动力学，从具有自旋能隙的顺磁体到Neel态的主跃迁。杂质自旋极化率在量子临界耦合处具有类居里发散，但具有既不是整数也不是半奇数的普适有效自旋。在尼尔态，横向杂质磁化率是一个通用数除以主体自旋刚度（决定了尼尔序方向上减慢扭曲的能量成本）。热力学、奈特位移和磁振子阻尼的这些结果和许多其他结果在层状过渡金属氧化物的实验中有重要的应用。
The spin dynamics of an arbitrary localized impurity in an insulating two-dimensional antiferromagnet, across the host transition from a paramagnet with a spin gap to a Neel state, is described. The impurity spin susceptibility has a Curie-like divergence at the quantum-critical coupling, but with a universal effective spin that is neither an integer nor a half-odd integer. In the Neel state, the transverse impurity susceptibility is a universal number divided by the host spin stiffness (which determines the energy cost to slow twists in the orientation of the Neel order). These and numerous other results for the thermodynamics, Knight shift, and magnon damping have important applications in experiments on layered transition metal oxides.