Pressure-induced Fermi-liquid behavior in the Kondo insulator SmB₆: Possible transition through a quantum critical point

We have investigated the electrical resistivity of the intermediate valence narrow-gap semiconductor SmB₆ at temperatures below 80 K and under pressure in the range between 1 bar and 70 kbar. We report on a continuous suppression of the gap under pressure, and on the observation of a critical point at p_cr≈40kbar, characterizing the pressure induced transition from a Kondo insulator below p_cr to a metallic heavy fermion liquid well above p_cr. In the metallic phase close to p_cr strong indications for a non-Fermi-liquid region, in which the electrical resistivity can be described by a power law ρ(T)=ρ₀+ATⁿ with 1<~n<~2, were observed.