Magnetism in Body-Centered Tetragonal FeRh_1−xPd_x Alloys (II) Band Structure

First-principle spin-polarized band calculations were performed for the body-centered tetragonal FeRh_1−xPd_x alloys with x=0, 0.5 and 1 as a function of the axial ratio c/a using the LMTO method. The energetically competing ferromagnetic and antiferromagnetic states were found to exist in bcc FeRh and bct FeRh_0.5Pd_0.5, as experimentally expected. The substitution of Pd for Rh hardly changes the shape of the density of states but simply raises the Fermi level when the axial ratio is fixed at a constant value. The tetragonal lattice elongation removes the degeneracy of the Fe d-band, and a large peak of DOS in the minority spin band for the bcc structure splits into two peaks for the bct structure, resulting in a reduction of the Fe magnetic moment. The large tetragonal elongation in the FeRh_1−xPd_x system is induced by the band Jahn-Teller effect.