Altermagnetism in NiSi and Antiferromagnetic Candidate Materials with Non-Collinear Spins

Recently, a new class of magnetic phenomenon, called altermagnetism, is proposed where the underlying spin configuration resembles antiferromagnetic structure, but the system violates PT (PT: Parity times Time reversal) symmetry due to the alternation of crystalline symmetry across magnetic ions. Although the original idea is proposed for the collinear spin structure, a recent report by Cheong et al. has suggested that antiferromagnetic materials with non-collinear spin structure and local alternation of crystalline arrangement can also manifest altermagnetism. Besides breaking the PT symmetry, altermagnetic compounds are also expected to exhibit anomalous Hall effects of odd orders. Here, possible candidates are discussed in this regard. One example is nickel monosilicide, which is recently shown to exhibit high temperature antiferromagnetism with non-collinear spin structure. It fulfills both criteria of breaking the PT symmetry and manifesting nonlinear anomalous Hall effect. In addition to NiSi, other potential antiferromagnetic materials are also discussed with non-collinear spin configuration for the exploration of altermagnetic states.