Large non-saturating Nernst thermopower and magnetoresistance in compensated semimetal ScSb

Abstract

Today, high-performance thermoelectric and thermomagnetic materials operating in the low-temperature regime, particularly below the boiling point of liquid nitrogen remain scarce. Most thermomagnetic materials reported to date exhibit a strong Nernst signal along specific crystallographic directions in their single-crystal form. However, their performance typically degrades significantly in the polycrystalline form. Here, we report an improved Nernst thermopower of $\sim 128\mu$V/K at 30 K and 14 T in polycrystalline compensated semimetal ScSb, in comparison to that was observed in single crystal ScSb previously. The magnetic field dependence of Nernst thermopower shows a linear and non-saturating behavior up to 14 T. The maximum Nernst power factor reaches to $\sim 240\times 10^{-4}$ W m⁻¹ K⁻² and Nernst figure of merit reaches to $\sim 11\times 10^{-4}$ K⁻¹. Polycrystalline ScSb also shows a large non-saturating magnetoresistance of $\sim 940\text{\%}$ at 2 K and 14 T. These enhanced properties originate from better electron–hole compensation, as revealed by Hall resistivity measurements. The cubic symmetry and absence of anisotropy in ScSb allow its polycrystalline form to achieve similar enhanced thermomagnetic and electromagnetic performance comparable to that of the single crystal.