Arthur T Knackerbracket has processed the following story:
Superconductors are the key to lossless current flow. However, the realization of superconducting diodes has only recently become an important topic of fundamental research. An international research team involving the theoretical physicist Mathias Scheurer from the University of Innsbruck have now succeeded in reaching a milestone: the realization of a superconducting diode effect without an external magnetic field, thus proving the assumption that superconductivity and magnetism coexist. They report on this in Nature Physics.
One speaks of a superconducting diode effect when a material behaves like a superconductor in one direction of current flow and like a resistor in the other. In contrast to a conventional diode, such a superconducting diode exhibits a completely vanishing resistance and thus no losses in the forward direction. This could form the basis for future lossless quantum electronics. Physicists first succeeded in creating the diode effect about two years ago, but with some fundamental limitations. "At that time, the effect was very weak and it was generated by an external magnetic field, which is very disadvantageous in potential technological applications," explains Mathias Scheurer from the Institute of Theoretical Physics at the University of Innsbruck.
The new experiments carried out by experimental physicists at Brown University, described in the current issue of Nature Physics, do not require an external magnetic field. In addition to the aforementioned application-relevant advantages, the experiments confirm a thesis previously theorized by Mathias Scheurer: Namely, that superconductivity and magnetism coexist in a system consisting of three graphene layers twisted against each other. The system thus virtually generates its own internal magnetic field, creating a diode effect.
More information:Jiang-Xiazi Lin et al, Zero-field superconducting diode effect in small-twist-angle trilayer graphene, Nature Physics (2022). DOI: 10.1038/s41567-022-01700-1
Journal information: Nature Physics
(Score: 2) by drussell on Saturday August 20 2022, @04:51PM (1 child)
I hadn't heard of this possible effect before, even the magnetic-field kind...
Does anyone know how high the resistance is in the reverse direction? Like, is this effect really, actually a decent diode in concept or does the resistance only increase slightly, like back to non-superconducting levels or whatever?
(Score: 1, Informative) by Anonymous Coward on Saturday August 20 2022, @11:08PM
Here is the arXiv paper [arxiv.org]. It looks like it goes from tens of kΩ to zero and back at a temperature in the milliKelvins, but I'm trying to pick that out of the paper figures (Figure 2) and not the text, so I might be taking something out of context.
(Score: 2) by Ken_g6 on Sunday August 21 2022, @02:30PM
I have never understood why a diode, preferentially allowing current in one direction, doesn't set up a current by itself and violate the laws of thermodynamics. This one doubly so, since it has zero resistance in one direction.