Effects of fabrication routes and material parameters on the control of superconducting currents by gate voltage
Leon Ruf, Tosson Elalaily, Claudio Puglia, Yurii P. Ivanov, François Joint, Martin Berke, A. Iorio, Péter Makk, Giorgio De Simoni, Simone Gasparinetti, Giorgio Divitini, Szabolcs Csonka, Francesco Giazotto, Elke Scheer, Angelo Di Bernardo
Abstract
The control of a superconducting current via the application of a gate voltage has been recently demonstrated in a variety of superconducting devices. Although the mechanism underlying this gate-controlled supercurrent (GCS) effect remains under debate, the GCS effect has raised great interest for the development of the superconducting equivalent of conventional metal-oxide semiconductor electronics. To date, however, the GCS effect has been mostly observed in superconducting devices made by additive patterning. Here, we show that devices made by subtractive patterning show a systematic absence of the GCS effect. Doing a microstructural analysis of these devices and comparing them to devices made by additive patterning, where we observe a GCS, we identify some material and physical parameters that are crucial for the observation of a GCS. We also show that some of the mechanisms proposed to explain the origin of the GCS effect are not universally relevant.