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Simple Mechanism Explains Field Effect in Superconducting Metals

Researchers from Lancaster University have shown that the latest “discovery” of the field-effect in superconductors by other physicists is nothing but hot electrons in the end.

Superconducting circuits find applications in sensing and information processing. Image Credit: Lancaster University.

At Lancaster, a research group from the Physics Department has discovered new and convincing proof that the observation of the field effect in superconducting metals by another team could be described by an easy mechanism that involves the injection of electrons, without requiring novel physics.

Our results unambiguously refute the claim of the electrostatic field effect claimed by the other group. This gets us back on the ground and helps maintain the health of the discipline.

Dr Sergey Kafanov, Lancaster University

The experimental group includes Ilia Golokolenov, Andrew Guthrie, Yuri Pashkin, and Viktor Tsepelin. Their study has been reported in the latest issue of Nature Communications journal.

When some metals are cooled to a few degrees exceeding absolute zero, their electrical resistance disappears—a remarkable physical phenomenon called superconductivity. Several metals, such as vanadium, which was utilized in the experiment, are well-known to display superconductivity at adequately low temperatures.

For many years, it was believed that the remarkably low electrical resistance of superconductors must make them possibly impenetrable to static electric fields, as a result of the method the charge carriers can easily organize themselves to redress for any external field.

Thus, it came as a shock to the physics community when several recent publications alleged that adequately strong electrostatic fields could impact superconductors in nanoscale structures—and tried to describe this new effect with comparable new physics. An associated effect is prominent in semiconductors and hence it forms the basis for the complete semiconductor industry.

The Lancaster group fixed a similar nanoscale device into a microwave cavity, thereby enabling them to study the so-called electrostatic phenomenon at much shorter timescales compared to what was examined earlier.

At short notice, the researchers were able to see a clear rise in the noise and energy loss in the cavity—the properties that are strongly related to the temperature of the device. They suggest that at strong electric fields, high-energy electrons have the ability to “jump” into the superconductor, thereby increasing the temperature and thus raising the dissipation.

This easy phenomenon can briefly describe the origin of the “electrostatic field effect” in nanoscale structures, without the help of any new physics.

Journal Reference:

Golokolenov, I., et al. (2021) On the origin of the controversial electrostatic field effect in superconductors. Nature Communications.


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