Electronic structure, chemical bonding and magnetism of the metal-rich borides MRh6B3 (M = Cr, Mn, Fe, Co, Ni) with Th7Fe3-type structure: A density functional theory study

The electronic structures, magnetic properties and chemical bonding of MRh6B3 (M = Cr, Mn, Fe, Co, Ni) were analyzed theoretically by first-principles density functional theory. All functionals used correctly reproduced the magnetic state of all experimentally characterized phases MRh6B3 (M = Cr, Fe, Co, Ni). In addition, ferromagnetic ordering is predicted in MnRh6B3, which is yet to be synthesized and characterized, with a magnetic saturation moment predicted to lie between 3.55 μB (LDA) and 4.07 μB (GGA). Linear muffin tin orbital (LMTO) calculations were applied to study the chemical bonding and magnetism in all phases. These calculations show that the Rh–B contacts are responsible for the structural stability, while the Rh–M interactions influence the magnetic behavior, whereas the M–B interactions regulate the variation of the unit cell volume in the series. The non-vanishing DOS values at all Fermi levels suggest metallic character for all phases as expected for these intermetallic compounds.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Electronic structures of MRh6B3 phases calculated. ► Ferromagnetism induced by 3d–4d magnetic interactions. ► MnRh6B3 predicted to order ferromagnetically. ► Rh–B bonds responsible for structural stability. ► M–B interactions regulate the volume trend.