Magnetic and transport properties of Te doped Yb14MnSb11

Abstract

A series of single crystal samples, Yb₁₄MnSb_11−xTe_x (x ≤ 0.2), were investigated via Sn flux. The element distributions were mapped using an electron microprobe, which demonstrated inhomogeneity and limited solubility of Te in the crystals. The magnetic properties of two crystals of compositions Yb_13.80(2)Mn_1.03(1)Sb_11.11(4)Te_0.06(3) and Yb_13.82(3)Mn_1.02(1)Sb_11.02(8)Te_0.14(6) were investigated. Increasing amounts of Te increase the saturation moment of Yb₁₄MnSb_11−xTe_x, and slightly lower the ordering temperature T_C by about 1 K. This is attributed to the filling of the hole in Yb₁₄MnSb₁₁ and the reduction of the screening of the Mn²⁺ d⁵ electrons, resulting in a higher effective moment. Hot-pressed, fully dense pellets of Yb_13.72(3)Mn_1.08(1)Sb_11.13(6)Te_0.07(5), Yb_13.76(5)Mn_1.11(1)Sb_10.96(8)Te_0.16(8), and Yb_13.76(4)Mn_1.10(2)Sb_10.95(9)Te_0.19(7) were prepared for thermoelectric property measurements. Both Seebeck coefficient and electrical resistivity increase with increasing amount of Te as a result of decreasing carrier concentration. Increasing amounts of YbTe with increasing x could be identified in the electron microprobe. The total thermal conductivity was approximately the same for all compositions, similar to that of Yb₁₄MnSb₁₁. The figure of merit zT reaches a maximum of 1.11 for x = 0.07 at 1240 K, which is approximately 12% higher than the parent compound, Yb₁₄MnSb₁₁.