正交铝磁钙钛矿中自旋劈裂与霍尔输运的对称性指导设计原则

中文摘要 AI 辅助

磁对称性即使在缺乏自旋轨道耦合（SOC）的情况下也能产生动量依赖的自旋劈裂电子能带，从而催生了最近发现的铝磁体（altermagnets）这一材料类别。在此，我们通过将自旋与磁群理论与第一性原理计算相结合，为正交Pbnm钙钛矿中的共线反铁磁体建立了一个统一的对称性框架。我们证明，磁有序的不可约表示唯一地决定了支持铝磁自旋劈裂的动量空间平面、有效低能哈密顿量的形式、SOC诱导的弱铁磁倾斜的方向以及允许的异常霍尔电导率（AHC）张量分量。这些预测在八种实验实现的正交钙钛矿氧化物中得到了验证，涵盖了绝缘体和金属态。特别是，LaTiO3和CaCrO3尽管净磁化强度几乎为零，却分别表现出约38和205 S/cm的可观异常霍尔电导率。我们进一步表明，SOC间隙对称性保护了铝磁能带交叉，产生了大的贝里曲率，而霍尔响应的根本基础在于潜在的非相对论性自旋劈裂。我们的工作建立了一个可预测的基于对称性的框架，用于发现和设计具有可调自旋依赖电子和输运性质的铝磁材料。

英文摘要

Magnetic symmetry can generate momentum-dependent spin-split electronic bands even in the absence of spin-orbit coupling (SOC), giving rise to the recently discovered class of altermagnets. Here, we establish a unified symmetry framework for collinear antiferromagnets in orthorhombic Pbnm perovskites by combining spin and magnetic group theory with first-principles calculations. We show that the irreducible representation of the magnetic order uniquely determines the momentum-space planes supporting altermagnetic spin splitting, the form of the effective low-energy Hamiltonian, the orientation of SOC-induced weak ferromagnetic canting, and the allowed anomalous Hall conductivity (AHC) tensor components. These predictions are validated in eight experimentally realized orthorhombic perovskite oxides spanning both insulating and metallic regimes. In particular, LaTiO3 and CaCrO3 exhibit sizable anomalous Hall conductivities of approximately 38 and 205 S/cm, respectively, despite nearly vanishing net magnetization. We further show that SOC gaps symmetry-protected altermagnetic band crossings, generating large Berry curvature, while the Hall response is fundamentally rooted in the underlying non-relativistic spin splitting. Our work establishes a predictive symmetry-based framework for discovering and engineering altermagnetic materials with tunable spin-dependent electronic and transport properties.

发表机构

• Indian Institute of Technology Bombay（印度理工学院孟买分校）

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