Specific heat and NMR evidence for the low Fermi-level density of states in semimetallic ScSb

Abstract

We report the electronic and thermal properties of scandium monoantimonide ScSb by means of the Seebeck coefficient, thermal conductivity, specific heat, and nuclear magnetic resonance measurements. The experimental Seebeck coefficient exhibits a strong temperature dependence, and the theoretical calculation based on the two-band model provides a realistic description of the observed feature. The analysis of the thermal conductivity reveals that the lattice thermal conductivity dominates at low temperatures while electronic thermal conductivity makes a major contribution at high temperatures. A small value of the Sommerfeld coefficient of $0.38\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}\phantom{\rule{0.16em}{0ex}}\mathrm{mo}{\mathrm{l}}^{\text{--}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\text{--}2}$ was extracted from the low-temperature specific heat measurement, indicative of a low electronic Fermi-level density of states (DOS) in ScSb. Furthermore, we have deduced the Sc $3d$ and Sb $5s$ partial Fermi-level DOSs based on the Korringa behavior in the $^{45}\mathrm{Sc}$ and $^{121}\mathrm{Sb}$ NMR spin-lattice relaxation rates. The determined values of the DOS are quite low, giving strong evidence for the semimetallic character in ScSb.