Effect of pressure on the correlation gap in a compound with intermediate valency SmB6
Berman I. V., Brandt N. B., Moshchalkov V. V., Pashkevich S. N., Sidorov V. I., Konovalova E. S., Paderno Yu. B.
It is found that the correlation gap E9 in SmB6, which under normal pressure —4 meV, decreases under the action of pressure ρ and vanishes at/? ^55 kbar. In the pressure range ρ > 60 kbar, the resistance of SmB6 as a function of temperature R (T) exhibits a metallic behavior, which indicates a pressure-induced transition of samarium in SmB6 from the state with intermediate valency ν [v(Sm) = 2.6 at ρ = 0] to integer valency ν = 3 for ρ > 60 kbar.