Nonlinear Piezomagnetism in Antiferromagnetic Dirac System

Piezomagnetism (PZM) is characterized by a linear coupling between magnetization and mechanical strain in crystals.  Recent work proposes that PZM can be realized in the C-paired spin valley locking (SVL) system with finite doping.  Here we systematically investigate PZM in strained C-paired SVL systems and conclude two scenarios where one needs finite doping and the other does not.  Particularly, in antiferromagnetic (AFM) Dirac systems with C-paired SVL,  PZM in the second scenario can present a nonlinear coupling between net magnetization and strain.  We refer to this nonlinear coupling in the Dirac system as nonlinear PZM, which is beyond the PZM with linear coupling in the previous works.  Via first-principles calculation,   this nonlinear PZM is predicted to exist in monolayer AFM Fe₂S which is a C-paired SVL system with Dirac cones. In sum, we discover nonlinear PZM in the Dirac system, which not only offers a more comprehensive understanding of PZM but also provides more opportunities for the device application of AFM materials.