Role of Coexistence of Superconductivity and Paramagnetism in Magnetostriction of High-Tc Superconductors

Total magnetostriction in the superconducting state for high Tc superconductors has been separated into critical state and paramagnetic components in terms of a H(x) dependent magnetic flux density. We show that the paramagnetic part is χ(2+χ)〈H(x)2〉, where χ is paramagnetic susceptibility. We have reproduced successfully ΔL/L−Ha curves measured by de la Fuente et al. (Phys. C 244:214, [1995]), in which they clearly observed coexistence of superconductivity and paramagnetism, employing the concepts presented in this work.