No abstract

We report transport properties of Sb 2−x Sn x Te 3 (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 Sb 2 Te 3 becomes n-type with a suitable doping engineering.

We report thermoelectric and electrical transport properties of Bi 1.8 Sb 0.2 Te 3-y Se y by tuning y. In contrast to the reported p-type conductivity of the end compounds with y ¼ 0 and 3, a dominant n-type conduction mechanism is observed for y ¼ 1.5 from the Hall measurement. Intriguingly, the magneto-Seebeck consequence is enhanced up to $ 20 times for y ¼ 1.5 compared to the end members. The reasonable value of magnetoresistance with an anisotropic character with respect to the direction of the magnetic field is observed at low temperature, which decreases with increasing temperature. The density of state at the Fermi level near room temperature correlates high Seebeck coefficient as well as magneto-Seebeck effect. High magneto-Seebeck effect at room temperature is promising for the application.

No abstract

No abstract