二维狄拉克四极自旋磁体中的拓扑压磁效应
Topological piezomagnetic effect in two-dimensional Dirac quadrupole altermagnets
AI总结：
本文研究了二维狄拉克四极自旋磁体的压磁效应，揭示其拓扑极化率源于拓扑响应理论，通过两个微观模型展示应变对狄拉克点四极结构的影响。
摘要：
自旋磁体为研究和利用压磁性提供了自然平台。本文引入了一类二维绝缘自旋磁体，称为狄拉克四极自旋磁体，并基于微观最小模型表明此类自旋磁体的轨道压磁极化率具有拓扑贡献，由拓扑响应理论描述。狄拉克四极自旋磁体的低能电子结构可通过无能隙的父相（即狄拉克四极半金属）理解，这对它们对外部场的响应有重要影响。聚焦应变诱导响应，本文证明拓扑压磁效应是应变影响狄拉克点四极结构的方式所导致的。我们考虑了两种微观模型：一种是描述s和d态能带倒转的无自旋两带模型，另一种是具有列线聂利顺序的利布晶格模型。后者是二维自旋磁体的典型最小模型，并在最近提出的若干材料化合物中实现。
英文摘要：
Altermagnets provide a natural platform for studying and exploiting piezomagnetism. In this paper, we introduce a class of insulating altermagnets in two dimensions (2D) referred to as Dirac quadrupole altermagnets, and show based on microscopic minimal models that the orbital piezomagnetic polarizability of such altermagnets has a topological contribution described by topological response theory. The essential low-energy electronic structure of Dirac quadrupole altermagnets can be understood from a gapless parent phase (i.e., the Dirac quadrupole semimetal), which has important implications for their response to external fields. Focusing on the strain-induced response, here we demonstrate that the topological piezomagnetic effect is a consequence of the way in which strain affects the Dirac points forming a quadrupole. We consider two microscopic models: a spinless two-band model describing a band inversion of $s$ and $d$ states, and a Lieb lattice model with collinear Néel order. The latter is a prototypical minimal model for altermagnetism in 2D and is realized in a number of recently proposed material compounds, which are discussed.
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