First-principles investigation of the magnetic structures and pressure-induced magnetic phase transition in magnetocaloric MnRhAs

Study of magnetic couplings in Fe2P-type MnRhAs indicate that indirect Mn⋯Mn exchange couplings dominate in MnRhAs, which were rationalized by RKKY and superexchange mechanisms. Moreover, there is a competition between ferromagnetic (FM) and antiferromagnetic (AFM) interactions of inter-layer exchange couplings, and their strengths are very sensitive to changes of volume. As pressure decreases, FM inter-layer Mn-Mn interactions become dominant, which causes the AFM-to-FM magnetic phase transition observed for MnRhAs.115