Precision measurements of the AC field dependence of the superconducting transition in strontium titanate

TL;DR

This study investigates how small AC magnetic fields affect the superconducting transition in strontium titanate, revealing extreme sensitivity that impacts accurate measurement and understanding of its pairing mechanism.

Contribution

The paper provides the first detailed analysis of the AC field dependence of the superconducting transition in strontium titanate using combined susceptibility and transport measurements.

Findings

Strontium titanate is highly sensitive to small AC fields.

AC fields influence the resistive transition significantly.

Extreme vortex sizes and mobilities are involved.

Abstract

Strontium titanate has resurfaced as a material prompting vigorous debate about the origin of its superconductivity in the extremely low carrier concentration regime. Here, we used simultaneous AC susceptibility and transport methods to explore the superconducting phase transition region in this material. We determined that strontium titanate is extremely sensitive to even small AC fields, which also influence the resistive transition; we suggest that extreme vortex sizes and mobilities contribute to this large effect. Our findings will be of importance for accurately determining transition temperature, informing the debate about the pairing mechanism in strontium titanate, for which even millikelvin errors may be critical.