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Title: Enhancing the critical temperature of strained Niobium films
Abstract

The study of the high critical temperature (Tc) of hydrogen compounds under high pressure has resulted in a considerable focus on Bardeen–Cooper–Schrieffer superconductors. Nb has the highestTcamong the elemental metals at ambient pressure, so reviewing Nb films again is worthwhile. In this study, we investigated the factors that determine theTcof Nb films by strain introduction and carrier doping. We deposited Nb films of various thicknesses onto Si substrates and evaluated theTcvariation with thickness. In-plane compressive strain in the (110) plane due to residual stress reduced theTc. First-principles calculations showed that adjusting the density of states at the Fermi level is key for both strain-induced suppression and doping-induced enhancement of the NbTc. The application of hydrostatic pressure compensated for the intrinsic strain of the film and increased itsTc, which could also be enhanced by increasing the hole concentration with an electric double-layer transistor. A liquid electrolyte should be used as a pressure medium for applying hydrostatic pressure to increase theTcof correlated materials, where this increase results from changes in material structure and carrier concentration.

 
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NSF-PAR ID:
10303659
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
IOP Publishing
Date Published:
Journal Name:
Materials Research Express
Volume:
7
Issue:
7
ISSN:
2053-1591
Page Range / eLocation ID:
Article No. 076001
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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