Switching effect in metal-superconductor-metal Fe(Te0.7Se0.3) nanojunction*

We report our transport study on the metal-superconductor-metal (MSM) device based on Fe(Te0.7Se0.3) nanoflakes. An unusual switching behavior in I-V characteristics for flakes with a thickness below 10nm has been observed. Furthermore, we discovered that such switching behavior could be controlled by an external magnetic field and bias voltage. Given the traditional understanding that superconductivity in Fe(Te0.7Se0.3) manifests as the collective effect from clusters of nanoscale superconducting domains, we proposed a self-heating model to explain such switching behavior. Our work demonstrates that nanoscale junction between superconducting and normal metal naturally exists in thin Fe(Te0.7Se0.3) nanoflakes, which provides an opportunity to study transport behavior MSM junction in nanoscale.