Interplay between positive magnetoresistance and thermoelectric properties by tuning carrier concentration in Sb2−xSnxTe3 (x ⩽ 0.05) crystals

Abstract

We report transport properties of Sb2−xSnxTe3 (x ⩽ 0.05) single crystals, where the tuning of the charge carrier densities via Sn doping significantly improves the magnetoresistance (MR) and the thermoelectric (TE) properties. The MR increases significantly at 2 K for x = 0.01, which reduces considerably with further Sn doping at x = 0.05. The MR results below 90 K for x = 0.01 satisfy the semi-classical two-band approach of Kohler’s rule, which does not satisfy the MR results for x = 0.05. At 300 K, the Seebeck coefficient (S) is positive and small for x = 0.01 and it changes the sign with the further increase in Sn doping at x = 0.05 at 300 K. The value of |S| is considerable with an enhancement of the thermoelectric power factor compared to the value for x = 0.01 at 300 K. Analysis of the Hall conductivity indicates the interplay between carrier mobilities and densities, leading to the tuning of MR and TE properties with Sn doping. These results demonstrate that the p-type Sb2Te3 becomes n-type with a suitable doping engineering.