Doubling the superconducting transition temperature of ultraclean wafer-scale aluminum nanofilms
Journal
Physical Review Materials
Journal Volume
7
Journal Issue
11
Start Page
114801
ISSN
2475-9953
Date Issued
2023-11-03
Author(s)
Ching-Chen Yeh
Thi-Hien Do
Pin-Chi Liao
Chia-Hung Hsu
Yi-Hsin Tu
Hsin Lin
T.-R. Chang
Siang-Chi Wang
Yu-Yao Gao
Yu-Hsun Wu
Chu-Chun Wu
Yu An Lai
Ivar Martin
Sheng-Di Lin
Christos Panagopoulos
Abstract
We studied the role of reduced dimensionality and disorder in the superconducting properties of wafer-scale aluminum (Al) nanofilms. This new generation of ultrathin films were grown using molecular beam epitaxy and depict normal-state sheet resistance at least 20 times lower than the quantum resistance h/(4e2). Defying general expectations, the superconducting transition temperature of our films increases with decreasing Al film thickness, reaching 2.4 K for a 3.5-nm-thick Al film grown on GaAs: twice that of bulk Al (1.2 K). Surface phonon softening is shown to impact superconductivity in pure ultrathin films, offering a route for materials engineering in two dimensions.
Publisher
American Physical Society (APS)
Type
journal article