Electric field control of superconducting fluctuations and quasiparticle interference at oxide interfaces
/ Authors
G. Kimbell, Ulderico Filippozzi, S. Gariglio, M. Gabay, A. Glatz, A. Varlamov, A. H. I. O. Physics, U. Geneva, Geneva, Switzerland.
and 23 more authors
Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands, Laboratoire de Physique des Solides, U. Saclay, Cnrs Umr 8502, Orsay Cédex, France, M. Division, A. N. Laboratory, Argonne, Illinois, Usa, Department of Applied Physics, Northern Illinois University, DeKalb, Institute of Superconductivity, I. Rome, Italy, L. I. O. Sciences, Letters, Milan
/ Abstract
We investigate tunable superconducting transitions in (111)$\mathrm{LaAlO}_3/\mathrm{KTaO}_3$ field-effect devices. Large increases in conductivity, associated with superconducting fluctuations, are observed far above the transition temperature. However, the standard Aslamazov-Larkin paraconductivity model significantly underestimates the effect observed here. We use a model that includes conductivity corrections from normal state quasiparticle interference together with all contributions from superconducting fluctuations evaluated at arbitrary temperatures and in the short-wavelength limit. Through analysis of the magnetoconductance and resistive transitions, we find that the large conductivity increase can be explained by a combination of weak anti-localization and Maki-Thompson superconducting fluctuations. Both contributions are enabled by a strong temperature dependence of the electron's decoherence time compatible with an electron-phonon scattering scenario. We find that conductivity corrections are modulated by the electrostatic field effect, that governs a competition between normal-state quasiparticle interference and superconducting fluctuations.