Insights into anomalous magnetic hyperfine field at Ce impurity in LaMn2X2 (X=Si, Ge)

Abstract

The LaMn2X2 (X=Si, Ge) intermetallic compounds doped with cerium exhibit the interesting physical effects that are typical of the REMn2X2 (RE=rare earth) series (such as magnetocaloric, superconductivy) or are originated from cerium in specific electronic environment (e.g. Kondo, intermediate valence, strongly correlated electron). Recently, the magnetic hyperfine field (mhf) at 140Ce-doped LaMn2(Si(1-x)Gex)2 was determined by perturbed gamma-gamma angular correlation spectroscopy. The 140Ce mhf follow the host magnetization in LaMn2Si2, while in LaMn2(Si(1-x)Gex)2 (with x = 0.2 up to 1), it has anomalous behaviour, which was associated with 4f cerium mhf contribution. In this work, first principles band structure simulations were used to improve the understanding of the distance role (generated by interchange of Si and Ge) on mhf cerium contribution.