外尔节点湮灭相变中RKKY相互作用的鲁棒性
Robustness of RKKY interactions across a Weyl node-annihilation transition
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中文总结 AI 辅助
本研究推导了双带自旋晶格系统的RKKY交换张量解析式，发现其在WSM的节点湮灭相变中保持鲁棒性，揭示RKKY相互作用由全带量子度量介导，为磁相互作用预测及相关模型构建提供了关键见解。
中文摘要 AI 辅助
具有独特拓扑性质和特殊电子结构的外尔半金属（WSM），在时间反演对称性或空间反演对称性破缺时会表现出引人关注的性质。本研究针对时间反演对称性破缺的WSM中的磁性杂质间的Ruderman-Kittel-Kasuya-Yosida（RKKY）相互作用展开研究，推导了任意双带自旋晶格系统中完整RKKY交换张量的解析表达式，该方法揭示了海森堡项、各向异性伊辛项以及Dzyaloshinsky-Moriya项，可通过对整个布里渊区的实空间格林函数进行能量积分计算，以带边作为天然能量截止。将该框架应用于时间反演对称性破缺WSM的双带紧束缚模型，该模型在具有分离手性节点的外尔相和二次带接触半金属相之间插值，值得注意的是，交换耦合的空间分布、大小及各向异性张量结构在节点湮灭相变中保持稳定，这种拓扑鲁棒性表明，短程和中程RKKY相互作用由整个价带的全局布里渊区积分量子度量介导，而非严格由局域低能贝里曲率单极子决定，这些发现证明了在预测实空间磁相互作用时采用全带紧束缚公式的必要性，为电场调控磁各向异性以及构建重费米子和外尔-近藤半金属的实际模型提供了关键见解。
英文摘要
Weyl semimetals (WSMs), with their unique topological properties and distinct electronic structure, exhibit intriguing properties when either time-reversal or inversion symmetries are broken. In this work, we consider the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between magnetic impurities in time-reversal symmetry-breaking WSMs. We derive analytical expressions for the full RKKY exchange tensor in arbitrary two-band spinful lattice systems. Our approach reveals both Heisenberg, anisotropic Ising and Dzyaloshinsky-Moriya terms, which can be calculated by energy-integrating real-space Green's functions across the entire Brillouin zone, with the band edge acting as a natural energy cutoff. We apply this framework to study a two-band tight-binding model for a time-reversal symmetry-breaking WSM that interpolates between a Weyl phase with well-separated chiral nodes and a quadratic band-touching semimetal phase. Remarkably, the spatial profile, magnitude, and anisotropic tensor structure of the exchange couplings remain persistent across the node-annihilation transition. This topological robustness reveals that short- and intermediate-range RKKY interactions are mediated by the global, Brillouin-zone-integrated quantum metric of the full valence band rather than being strictly dictated by local low-energy Berry curvature monopoles. These findings demonstrate the necessity of full-band tight-binding formulations when predicting real-space magnetic interactions, providing key insights for electric-field tuning of magnetic anisotropy and constructing realistic models of heavy-fermion and Weyl-Kondo semimetals.
发表机构
- Gleb Wataghin Institute of Physics, The University of Campinas (Unicamp)（吉布斯·瓦塔金物理研究所，坎皮纳斯大学）
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