Bulk properties of single crystals of the valence-unstable compound SmRh${}_2$Si${}_2$

Abstract

We present the crystal growth as well as the structural, chemical and physical chracterization of SmRh${}_2$Si${}_2$ single crystals. Their ground state is antiferromagnetic, as indicated by the behaviour of the magnetic susceptibility and the specific heat at the second order phase transition observed at T${}_{\mathrm{N}}$ = 64 K. The Sommerfeld coefficient is small and similar to that of LuRh${}_2$Si${}_2$ with ${\gamma }_0\approx$ J/(molK${}^2$). Susceptibility measurements show no Curie-Weiss behaviour at high temperatures which is a consequence of the large Van-Vleck contribution of the excited multiplets of Sm${}^{3+}$. Previous angle-resolved photoemission studies showed that at 10 K, the valence of the Sm ions is smaller than three at the surface as well as in the bulk, suggesting a possible Kondo screening of the Sm${}^{3+}$ ions. This could not be observed in our thermodynamic and transport measurements.