Low temperature specific heat of Sm1−xYxS

Abstract

The Sm1−xYxS system, in analogy is pure Sms under pressure, exhibits a large volume decrease and color change, from black to gold, with increasing x. Both effects are related to the proximity in energy of the Sm f5d configuration to the f6. Transport and lattice constant measurements by Penney and Holtzberg1 indicate that there is a much larger density of states at the Fermi energy in the gold phase than in the black phase. We have measured the low temperature (1.3°K to ∠12°K) specific heat of small (≲20 mg) single crystal samples cleaved from the same crystals used in preparing the transport samples. The results indicate an order of magnitude greater density of states in the gold phase than in the black, in agreement with the predictions of the model.