Magnetic properties, magnetoresistance, and electronic structure of cubic DyCu5

The magnetic properties, magnetoresistance (MR), and electronic structure o f the cubic phase (structure-type AuBe5, space group F-43m) of melt-spun Dy Cu5 have been investigated. In ac-susceptibility and magnetization measurem ents it has been found that below a critical temperature T-m = 7.5 K this p hase is metamagnetic. alpha DyCu5 samples show a negative magnetoresistance ratio MR(H) = [R(H) - R(0)]/R( 0) of about -27% at 10 K and 5 T. This effe ct has similar behavior in transverse and perpendicular current-field direc tions. The electronic structure of alpha DyCu5 was calculated by the ab ini tio self-consistent spin-polarized tight-binding linear muffin tin orbital method in the atomic sphere approximation for the experimental value of lat tice parameter a=0.7027 nm. The Fermi-level E-F is located at the minority 4f Dy band. The main contribution to the density of states at the E-F comes from 4f states of Dy and 3d states of copper atoms in one of two nonequiva lent positions in a crystallographic cell. (C) 1999 American Institute of P hysics. [S0021-8979(99)57608-1].