We present triple-axis neutron scattering studies of low-energy magnetic fluctuations in strongly underdoped La2−xSrxCuO4 with x=0.05, 0.06 and 0.07, providing quantitative evidence for a direct competition between these fluctuations and superconductivity. At dopings x=0.06 and x=0.07, three-dimensional superconductivity is found, while only a very weak signature of two-dimensional superconductivity residing in the CuO2 planes is detectable for x=0.05. We find a surprising suppression of the low-energy fluctuations by an external magnetic field at all three dopings. This implies that the response of two-dimensional superconductivity to a magnetic field is similar to that of a bulk superconductor. Our results provide direct evidence of a very gradual onset of superconductivity in cuprates.
@article{arxiv.2211.01733,
title = {Gradual emergence of superconductivity in underdoped LSCO},
author = {Ana-Elena Tutueanu and Machteld E. Kamminga and Tim B. Tejsner and Henrik Jacobsen and Henriette W. Hansen and Monica-Elisabeta Lacatusu and Jacob Baas and Kira L. Eliasen and Jean-Claude Grivel and Yasmine Sassa and Niels Bech Christensen and Paul Steffens and Martin Boehm and Andrea Piovano and Kim Lefmann and Astrid T. Rømer},
journal= {arXiv preprint arXiv:2211.01733},
year = {2023}
}