RESISTIVE AND MAGNETIC-ANOMALIES IN HIGH T-C CUPRATES

After the discovery of new high Te superconducting families [1-3], the possibility of Te close to room temperature is reexamined. Some diamagnetic and resistive contributions are clearly associated with superconducting fluctuations [4] extending up to 200K or more in Hg [5] and Cu cuprates. The possibility of traces of high temperature (T-c>250K) superconducting phases is also suggested by resistive and magnetic anomalies. However, resistive anomalies are not very reproducible due to ageing effects at room temperature, and paramagnetic contributions often dominate what could be considered as the onset of diamagnetism.