Sign reversal of the Hall resistivity in the electron-doped La2-xCexCuO4 thin films

摘要: The new superconducting system Sr2VO3-delta FeAs has been fabricated at different oxygen contents. It is found that the transition temperature drops monotonically with increase of deficiency and residual resistivity, indicating an anomalous pair breaking effect by disorders. Magnetotransport measurements reveal evolves from one-step-like low field to two-step-like high field. first step corresponds upper critical field, while second one related irreversibility line. A vortex phase diagram thus derived, which shows a large area liquid state. This indicates anisotropy system. Finally we present specific heat optimally doped sample (delta approximate 0.1) T-c = 40 K. coefficient appears in state, suggesting existence amount unpaired electrons may derive V-band. (C) 2010 Elsevier B.V. All rights reserved.