Transport and thermoelectric properties of Cr1−xMnxSb2 at low temperatures

Abstract

The effect of Mn substitution on transport and thermoelectric properties of Cr 1− x Mn x Sb 2 ( x = 0, 0.01, 0.03, 0.05) have been investigated at the temperatures from 7 K to 313 K. The results show that similar to CrSb 2 all the doped samples are semiconducting. However, electrical resistivity of Cr 1− x Mn x Sb 2 is found to decrease greatly with increasing doping content of Mn. Besides, Mn substitution leads to suppression of the plateau appearing in the plot of resistivity vs. temperature for CrSb 2 and makes the resistivity anomaly originating from antiferromagnetic transition shift to higher temperatures. Moreover, corresponding to the plateau a large peak of thermopower (−431 μV K −1 ) was observed at ∼60 K, which was also found to be suppressed by Mn doping. In addition, lattice thermal conductivity of Cr 1− x Mn x Sb 2 was found to decrease substantially with increasing Mn content, though Mn doping also results in slow reduction in absolute value of thermopower at the temperatures T > ∼200 K. As a result, at T > ∼260 K the figure of merit ZT of heavily doped sample Cr 1− x Mn x Sb 2 ( x = 0.03 and 0.05) was improved. Specifically, at 313 K ZT value of Cr 0.95 Mn 0.05 Sb 2 is ∼14% larger than that of CrSb 2 , indicating that thermoelectric properties of CrSb 2 can be improved by proper substitution of Mn for Cr.