发表机构
Indian Institute of Technology Bombay; Polish Academy of Sciences（印度理工学院孟买分校; 波兰科学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一个统一理论框架，通过扩展自旋-轨道模型统一描述交错磁体中由不等价环境与轨道序驱动的集体磁振子和轨道子激发及其手性劈裂。
AI 中文摘要
交错磁性最近作为一种独特的共线磁性相出现，尽管净磁化强度为零，但由于不等价的非磁性环境，它表现出动量依赖的自旋劈裂。近来，有人提出强电子关联可能由于轨道序而在即使等价非磁性环境下也产生自发交错磁性。虽然以往研究主要关注电子结构，但对于稳定交错磁性的这两种不同微观机制相关的集体激发，仍缺乏统一理解。在此，我们在一个装饰方格子上发展了一个扩展的Kugel'-Khomskiĭ自旋-轨道模型，在共同的理论框架内同时纳入不等价非磁性环境和关联驱动的轨道序。采用自洽平均场自旋波-轨道波形式，我们证明了相互不杂化但相互依赖的磁振子和轨道子激发的出现，这些激发表现出特征性的手性劈裂。我们表明，这种劈裂源于两种不同的微观贡献：一个来自不等价非磁性环境的晶格依赖项，以及一个轨道序诱导的交换各向异性项，后者即使在等价非磁性环境下也存在。因此，所提出的框架统一了与两种类型交错磁性相关的集体激发。我们进一步研究了耦合自旋-轨道系统的有限温度演化，揭示了通过虚假的一级相变导致自旋波和轨道波近似的失效，而互补的经典蒙特卡洛模拟恢复了预期的连续二级行为。我们的工作为理解交错磁体中的集体磁振子和轨道子激发建立了一个统一的微观框架。
英文摘要
Altermagnetism has recently emerged as a distinct collinear magnetic phase exhibiting momentum-dependent spin-splitting despite vanishing net magnetization, as a consequence of inequivalent non-magnetic environments. Lately, it has been proposed that strong electronic correlations may yield spontaneous altermagnetism due to orbital ordering even for equivalent non-magnetic environments. While previous studies have largely focused on the electronic structure, a unified understanding of the collective excitations associated with these two different microscopic mechanisms stabilizing altermagnetism remains absent. Here, we develop an extended Kugel'-Khomskiĭ spin-orbital model on a decorated square lattice that simultaneously incorporates inequivalent non-magnetic environments and correlation-driven orbital ordering within a common theoretical framework. Employing a self-consistent mean-field spin-wave orbital-wave formalism, we demonstrate the emergence of mutually unhybridized but interdependent magnon and orbiton excitations exhibiting characteristic chiral-splitting. We show that the splitting originates from two distinct microscopic contributions: a lattice-dependent term arising from inequivalent non-magnetic environments and an orbital-order-induced exchange-anisotropy term that survives even for equivalent non-magnetic environments. The proposed framework therefore unifies the collective excitations associated with both types of altermagnetism. We further investigate the finite-temperature evolution of the coupled spin-orbital system, revealing the breakdown of spin-wave and orbital-wave approximations through spurious 1st-order transitions, while complementary classical Monte Carlo simulations recover the expected continuous 2nd-order behaviour. Our work establishes a unified microscopic framework for understanding collective magnon and orbiton excitations in altermagnets.
Comments37 pages (19 pages main, 18 pages supplement), 5 figures (all in main), 1 table (in main)
