• field-effect
• superconductivity
• supercurrent transistor

The transport properties modulation of conventional metallic superconductors via the electrostatic field-effect was excluded due to the screening character of the normal state. In spite of this, a recent series of gating experiments demonstrated the complete and bipolar suppression of the critical current in all-metallic mesoscopic devices under the effect of an intense electric field (0.5 GV/m).

Although unexpected, this discovery reveals broad technological applicability. Indeed, a superconductive field-effect-transistor can benefit from both the power efficiency and speed advantages offered by the superconductor platform, and the capacity to interface with the conventional voltage-controlled technologies.

From the fundamental point of view, these observations still demand an exhaustive microscopic explanation. Nowadays, two alternative hypotheses are under investigation.
The electrostatic field could be responsible for the orbital polarization of the surface atomic layers of the metallic film, or to induce a current flowing between the gate electrode and the superconductive channel.

Here we examine this latter hypothesis. Guided by the experimental investigation exploiting a suspended Ti-based superconducting FET, the support of numerical Finite Element Method (FEM) simulations, and thermodynamic considerations, we discard any reasonable direct correlation between a possible gate-channel conduction mechanism and the critical current suppression process.