Numerical modeling of the superconducting flux flow transistor with a nanobridge

We have fabricated superconducting flux flow transistors (SFFTs) with a nanobridge from epitaxial superconducting thin films by photolithography and electron-beam lithography. We have tried to simulate their I-V characteristics by building a model. The simulation was performed by varying the penetration depth as a function of the width and the thickness in the nanobridge and the gate current. This model showed the dependence of the critical current density on the spatial distribution of an applied magnetic field induced by the gate current. The simulated I-V curves were well in agreement with the measured curves in the flux creep regime of an SFFT with a nano-scale channel. This model is suitable for prediction of the I-V characteristics in the flux creep regime of the SFFT with a nano-scale channel.