Insulator–metal transition studied by heat capacity measurements on SmS

Abstract

We have measured the specific heat of SmS at pressures up to ∼7.5 kbar . We have observed that the electronic specific heat coefficient γ shows a steep increase at around P c ∼3.5 kbar , which corresponds to an insulator–metal phase transition. In the metal phase above P c , we have found that γ reaches 100 mJ/mol K 2 , indicating a strongly correlated metallic state. In the insulator phase, on the other hand, we have observed an anomaly in the temperature dependence of the specific heat around 1 K , which seems to survive in the metal phase.