Effect of injected spins with different polarized orientations on the vortex phase transition in La_(0.7)Sr_(0.3)MnO_3/La_(1.85)Sr_(0.15)CuO_4 heterostructure

摘要

The current-voltage (Ⅰ-Ⅴ) characteristics with spin injection were investigated for the epitaxial La_(0.7)Sr_(0.3)MnO_3/La_(1.85)Sr_(0.15)CuO_4 heterostructure rotated from H//c to H//ab in magnetic fields up to 14 T. It is found that all the Ⅰ-Ⅴ curves in various magnetic fields can be scaled with a three dimensional (3D) vortex glass model, and the spin injection can induce a better 3D scaling behavior, which is closely related to the decrease of the anisotropy parameter. A vortex phase diagram for the evolution of vortex glass transition field (H_g) and upper critical field (H_(c2)) indicates that both H_g and H_(c2) are suppressed by spin injection, and this effect becomes more obvious in the case of H//ab, which probably originates from the different suppression on the superconducting pairing strength by different injected spins' orientations.