Coherent ferromagnetic precipitate and anomalies in the heat conduction and thermopower

摘要

The heat diffusivity D, the electrical resistivity p and thermoelectric power S of tetragonal Mn_2-xCr_x Sb single crystals with 0.02 ＜ x ＜0.12 have been measured in the temperature range of 90 K＜ T ＜ 350 K and along different crystal axes. The heat conductivity κ and σ=1/ρ are anisotropic along the crystal axes a, c with a ration of 2:1. κ(T), ρ(T) and S(T) show anomalies at the spin reorientation temperature T_Rm of the matrix(M) Mn_2-xCr_xSb, but also at that of the coherent ferromagnetic precipitate (P) Mn_1.037Cr0.11Sb,T_Rp which is assigned to variations in the spin depen- dent scattering at the M/P interfaces via changes in the relative orientation of the magnetization vectors of matrix and precipitate(spin valve effect).