Giant magnetostriction of cuprates in superconducting state

Abstract

Abstract Unusually large magnetostriction was found in a single crystal of high temperature superconductor Bi 2 Sr 2 CaCu 2 O 8 . 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 (La 1−x Sr x ) 2 CuO 4 ( x = 0.05) sample, the magnetostriction was smaller by two orders, but the shape of the magnetostriction curve exhibited many similarities with that of Bi 2 Sr 2 CaCu 2 O 8 . 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.