Modeling of I-V characteristics in a 3-channel SFFT with nanobridges by gate current signals

A superconducting flux flow transistor (SFFT) with three channels and nanobridges was successfully fabricated by electron beam (e-beam) lithography and an Ar ion milling technique. The SFFT is composed of three weak links with a nearby gate current line. We explain the process to obtain the equation for the current-voltage characteristics and describe the method to induce external and internal magnetic fields by Biot-Savart's law. The equation can be used to predict the current-voltage curves for the 3-channel SFFT fabricated using e-beam lithography. I-V characteristics were simulated to analyze the SFFT with three channels and nanobridges by a Matlab program. From the I-V characteristics equation of the 3-channel SFFT, the drain currents and the output voltages as the gate current is applied are graphically compared with the measured value and the simulation value. The simulated I-V curves were in good agreement with the measured curves of the 3-channel SFFT with nanobridges.