Deuteration-induced ferromagnetic metallic properties in R7Rh3Dx (R = Tb, Dy)

The magnetic and the electrical properties of the R 7Rh3 deuterides Tb7Rh3D27 and Dy7Rh3D27 have been studied by measuring the magnetization, magnetic susceptibility and electrical resistivity. Tb7Rh3D27 and Dy7Rh3D27 show a ferromagnetic property below T C = 62 K and 23.5 K, respectively; a metallic state is induced by deuteration. The deuteration-induced magnetic transition in these compounds can be realized by a competition between the inter- and intra-layer exchange interactions. The deuteration-induced semimetal to metal transition can be attributed to a modification of the energy band structure produced by a lattice expansion due to protons located in the interstitial positions and/or additional electrons originating from the dissociation of deuterium.