GIANT MAGNETOSTRICTION OF CUPRATES IN SUPERCONDUCTING STATE

Unusually large magnetostriction was found in a single crystal of high temperature superconductor Bi2Sr2CaCU208. The sample length change was measured along the ab-plane under magnetic field applied parallel to the c-axis up to 6 T. The relative sample length change which exceeded the order of 10(-4) at 4.8 K was negative during the field increasing process, and became positive by sweeping the field back to zero, giving rise to a large hysteresis. For a (La1-xSrx)2CU04 (X=0.05) sample, the magnetostriction was smaller by two orders, but the shape of the magnetostriction curve exhibited many similarities with that of Bi2Sr2CaCu2O8. The behavior of these magnetostriction curves can be well-explained by the compressive and expansive forces internally exerted within the crystal due to the flux pinning.