The Role of Temperature and Magnetic Field in Destroying a Superconducting Phase in a-Ta Thin Films

We investigated superconductor insulator transition induced by controlling temperature and magnetic field in the superconducting Tantalum thin films. Quantum metallic phase intervening superconducting and insulating phase were reproduced by increasing magnetic field at low temperature limit, which was characterized by the finite saturation in the electrical resistance as well as non-linear I-V characteristics without hysteresis. [PRB.73.100505(2006)]. Besides, we observed similar non-linear I-V characteristic behaviors with different features near the transition temperature. To clarify the role of temperature and magnetic field, we conducted precise dV/dI measurements as varying temperature and magnetic field. We found the non-linear IV characteristic and destruction of superconductivity could be understood in the framework of vortex dynamics with unpinning by thermal excitation and addition by magnetic field.