Structurally driven metamagnetism in MnP and related Pnma compounds

We investigate the structural conditions for metamagnetism in MnP and related materials using density-functional theory. A magnetic stability plot is constructed taking into account the two shortest Mn-Mn distances. We find that a particular Mn-Mn separation plays the dominant role in determining the change from antiferromagnetic to ferromagnetic order in such systems. We establish a good correlation between our calculations and structural and magnetic data from the literature. Based on our approach it should be possible to find Mn-containing alloys that possess field-induced metamagnetism and associated magnetocaloric effects.