MAGNETIZATION OF STRIPE PHASE SUPERCONDUCTORS

Magnetization measurements have been carried out for superconducting L a1.45Nd0.40 Sr0.15CuO4 in order to determine whether the the shape of the magnetization vs field (M vs H) curves for a stripe phase material are similar to classical superconductors and to other high temperatur e superconductors. Neutron scattering data have shown that this materi al is an antiphase domain antiferromagnet in which the holes collect i n the domain walls of the antiphase domain structure. With this locali zation of holes, the superconducting order parameter might be space de pendent and the vortex lattice might be different from ordinary Type I I superconductors. A large region of thermodynamic reversibility is fo und, and the flux expulsion data show that this material is a good bul k superconductor with a free energy difference between the superconduc ting and normal state very similar to a, classical superconductor like Nb. The shape of the magnetization curves (M vs H), however, has a do uble peak structure that is quite different from the predictions of cl assical Type II behavior and different from Y(123).