Elastic constants and specific-heat measurements on single crystals ofLa2CuO4

Abstract

We measured all nine elastic constants of a nonsuperconducting single crystal of ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ at 310, 297, and 44 K using a small-sample resonant ultrasound technique. Weak features in resonant frequencies dependent on compressional moduli were observed near 29 K, and a broad minimum occurred at 38 K, near the superconducting transition temperature of optimally doped ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$. The features are also reflected in the specific heat.