Effect of magnetic field on the photovoltaic properties of YBa_2Cu_3O(6.96)/Ag heteroj unction

摘要

The obvious photovoltaic effect (V_(oc) ~ 30 μV) induced by purple-laser illumination at high T_c superconductor YBa_2Cu_3O_(6.96)/Ag (YBCO/Ag) heteroj unction has been observed, revealing that there exists an electrical field across the YBCO/Ag interface. It has been found that magnetic field can dramatically change the photo-induced voltage in the vicinity of superconducting transition. With increasing magnetic fields up to 3 T, the photovoltage at 74 K and 30 mW/mm~2 is reduced from 15 μW to zero and then reaches —15 μV. The polarity of the voltage can be switched by applying an external magnetic field, as well as by varying the laser intensity. Our results can be understood in terms of the magnetic vortex penetrating in high T_c superconductors and provide strong evidence for the existence of an interface electrical field in the superconductor/metal heterojunction.