Density-tuned isotherms and dynamic change at phase transition in a gate-controlled superconducting system

TL;DR

This study investigates how the resistance of a SrTiO3-based heterostructure varies with gate voltage at different temperatures, revealing slow dynamics and structural influences on the superconducting phase transition.

Contribution

It provides the first detailed measurement of the timescale of dynamic changes during the superconducting phase transition in a gate-controlled 2D electron gas system.

Findings

Resistance shows non-monotonic behavior within the superconducting dome.

Timescale for phase transition dynamics is tens of seconds near superconductivity onset.

Structural defects significantly influence the kinetics of the phase transition.

Abstract

Two-dimensional electron gases in SrTiO3-based heterostructures provide a platform to study the real-time evolution of the macroscopic state with a variation of the carrier density, and the impact of structural properties on the emergence of the superconducting state. We have explored the isothermal evolution of the electron gas in AlOx/SrTiO3 by measuring the variation of resistance with continuous gate-voltage-controlled tuning of its carrier density. It is seen that condensation of the ordered phase leads to non-monotonic isotherms within the superconducting dome. The timescale for dynamic change following changes in gate voltage is measured across the phase transition. It is found to be tens of seconds near the onset of superconductivity, significantly larger compared to the normal state. Such a large timescale governing the kinetics of the phase transition presumably arises from the strong impact of structural defects and distortions of the substrate on the development of superconducting islands.