Discovery of superconducting diode effect with zero electrical resistance in one direction only

It could lead to electronic circuits that are less likely to generate heat.

Engadget JP (Translation)
Engadget JP (Translation) , @Engadget_MT
2020年08月24日, 午後 08:07 in egmt
Kyoto University
Kyoto University

This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl.

A research team consisting of researchers from the Institute for Chemical Research and the Graduate School of Science at Kyoto University and the Graduate School of Science at Osaka University announced that they have observed for the first time the superconducting diode effect, in which the electrical resistance is zero in one direction only.

A diode is an element consisting of two types of semiconductor materials joined together and has the property of passing current between two electrodes in only one direction. These elements are used to convert alternating current, which is periodically switched in one direction, into direct current, to prevent overvoltage in electric circuits, and to extract audio signals from radio waves.

However, since semiconductors have electrical resistance even when current is flowing, electronic circuits inevitably experience energy loss due to heat generation. If this resistance can be reduced to zero, that is, to a state of superconductivity, it will be possible to design electric circuits with low heat generation and low power consumption.

In this research, a thin film sample of a three-layered crystal lattice (an artificial superconducting lattice) was made of niobium, vanadium, and tantalum, which have superconducting properties, by a film deposition technique called sputtering. When an external magnetic field was applied to the thin film sample or in the direction perpendicular to the electric current, it was found that the limit value of the flowing current (Critical current. Beyond this value, superconductivity cannot be maintained and the resistance increases, resulting in a normal-conductive state) differed depending on the direction of the applied current. It was also found that the relationship between the critical current flowing in the forward direction and the critical current flowing in the reverse direction is dependent on the external magnetic field.

Using this difference in critical current, the sample can be switched between a superconducting and a normal-conductive state according to the direction of the current flow and the magnetic field, in other words, the sample can be given the function of a superconducting diode.This diode can be switched even in a relatively weak magnetic field of 0.02 T (Tesla).

If the superconducting diode can be put to practical use, it will be possible to create electronic circuits with very low heat generation. However, this research is still in its early stages, and there are still many things that remain unclear, such as the mechanism of how the critical current changes depending on the direction of the current. This will require further theoretical and experimental exploration. The search for new materials more suitable for electronic circuit applications is also likely to be carried out.

Source: Nature, Kyoto University (PDF)

This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl. The Japanese edition of Engadget does not guarantee the accuracy or reliability of this article.

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