Magnetoresistance studies of Ho_0.85Tb_0.15Mn_2-xFe_x (x=0, 0.25, 0.5, 1, and 2)

Abstract

Magnetoresistance (Δρ/ρ) studies have been carried out on the C15-type cubic Laves phase Ho_0.85Tb_0.15Mn_2-xFe_x (x=0, 0.25, 0.5, 1, and 2) compounds up to a magnetic field of 90 kOe at temperatures 5, 30, and 100K. The lattice parameters were found to decrease with increasing x. The Curie temperature is found to increase with increasing x from 30 to 680K, which is attributed to the net increase in the exchange splitting of the spin-up and spin-down bands. A maximum value of Δρ/ρ of -27% was observed for Ho_0.85Tb_0.15Mn₂ around the ordering temperature. This is explained on the basis of nearest Mn-Mn critical distance. A positive magnetoresistance, increasing in a discontinuous manner with increasing field, due to the dependence of scattering of conduction electrons on large magnetoelastic interactions, was observed at 5K in Ho_0.85Tb_0.15Fe₂.