Anisotropic physical properties of the Kondo semiconductor CeRhSb

Abstract

Measurements of resistivity \ensuremath{\rho}, thermopower S, and magnetic susceptibility \ensuremath{\chi} are reported on single-crystal CeRhSb. Only along the orthorhombic a axis, \ensuremath{\chi}(T) exhibits a pronounced peak at 13 K and \ensuremath{\rho}(T) has a shoulder at around 20 K. These anomalies and the relations ${\mathrm{\ensuremath{\rho}}}_{\mathit{c}}$\ensuremath{\gtrsim}${\mathrm{\ensuremath{\rho}}}_{\mathit{b}}$\ensuremath{\gtrsim}${\mathrm{\ensuremath{\rho}}}_{\mathit{a}}$ and ${\mathrm{\ensuremath{\chi}}}_{\mathit{a}}$\ensuremath{\gtrsim}${\mathrm{\ensuremath{\chi}}}_{\mathit{b}}$\ensuremath{\gtrsim}${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$ resemble those in the isostructural Kondo semiconductor CeNiSn. However, the anisotropy in \ensuremath{\rho}(T), \ensuremath{\chi}(T), and S(T) is still weaker than that in CeNiSn. The magnetic contribution to the specific heat divided by temperature ${\mathit{C}}_{\mathit{m}}$/T reveals a maximum of 0.1 J/${\mathrm{K}}^{2}$ mol near 10 K and decreases linearly with decreasing temperature. These results indicate that the gap formation in CeRhSb and CeNiSn originates from a similar type of hybridization of 4f states with a conduction state.