Thermodynamic phase diagram of the cubic (K,Ba)BiO sub(3) superconductor

Specific heat, transport and reversible magnetization measurements have been performed on high quality (K,Ba)BiO sub(3) single crystals (T sub(c) [similar to] 31 K). Calorimetric measurements up to 16 T show that the transition line between the superconducting and normal states has a strong anomalous positive curvature. The reversible magnetization deviates strongly from the standard London model above 0.8T sub(c) emphasizing the original nature of the superconducting transition in this system. copyright 2001 Elsevier Science B.V. All rights reserved.