Influence of Ni doping on the properties of perovskite molybdates SrMo_(1-x)Ni_xO_3 (0.02 ≤ x ≤ 0.08)

摘要

Systematic studies of the structural, transport, magnetic and specific heat behavior have been performed on the perovskite molybdates SrMo_(1-x)Ni_xO_3 (0.02 ≤ x ≤ 0.08). Ni doping at the Mo site does not change the structure of all samples, but increases the lattice parameter a monotonically. All of the doped samples keep their metallic behavior. The magnetic properties keep a Pauli paramagnetism in the high-temperature region, but have a ferromagnetic (FM) transition at about 50 K. The resistivity, ρ, and magnetic susceptibility, χ, increase, while the electronic specific heat coefficient, γ_e, decreases monotonically with the increase of Ni doping content, x. The electronic transport of all samples shows a T~2 dependence in the low-temperature region and a T dependence in the high-temperature region, respectively. The temperature dependence of the specific heat can be well described by the formula C_p(T)/T = γ_e + β_pT~2 in the low-temperature range. These behaviors can be explained by the competition between the decrease in the density of states (DOS) at the Fermi level and the electron localization due to the disorder effect induced by the random distribution of Ni at the Mo site in the samples.