Superconductivity, high critical temperature found in 2D semimetal W2N3

Date	5th, May 2021

Summary:

2D superconductors have drawn considerable attention both for the fundamental physics they display as well as for potential applications in fields such as quantum computing. Although considerable efforts have been made to identify them, materials with high transition temperatures have been hard to find. Materials featuring both superconductivity and non-trivial band topology have proven even more elusive. A recent Nano Letters paper predicts just such a material in the easily exfoliable, topologically non-trivial semimetal W2N3.

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image: The model predicts a remarkably high superconducting critical temperature of 21 K in the easily exfoliable, topologically nontrivial 2D semimetal W2N3. view more

Credit: Davide Campi @EPFL

Superconductivity in two-dimensional (2D) systems has attracted much attention in recent years, both because of its relevance to our understanding of fundamental physics and because of potential technological applications in nanoscale devices such as quantum interferometers, superconducting transistors and superconducting qubits.

The critical temperature (Tc), or the temperature under which a material acts as a superconductor, is an essential concern. For most materials, it is between absolute zero and 10 Kelvin, that is, between -273 Celsius and -263 Celsius, too cold to be of any practical use. Focus has then been on finding materials with a higher Tc.

While researchers have discovered materials that act as conventional superconductors at temperatures as high as 250 K under extreme pressure, the reported record until now among 2D materials stands at between 7 and 12K in MoS2 according to experimental evidence and up to 20 K in some doped 2D materials and in intrinsic 2D metals according to theoretical modelling. Theoretical predictions have put a superconducting transition at a temperature above liquid hydrogen for some recently realized 2D boron allotropes but these materials cannot be obtained by exfoliation from van der Waals-bonded 3D parents and must be grown directly on a metal substrate. This results in relatively strong interactions that are predicted to suppress the superconducting critical temperature down to just 2 K in a supported sample.

In parallel to this search for higher Tc, researchers have been looking for materials that combine nontrivial topological properties with superconductivity. This search is driven both by a quest for exotic states of matter as well as for deeper understanding of the interactions between topological edge states and the superconducting phase.

In the paper "

Source:

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