Point-contact Andreev reflection spectroscopy of layered superconductors with device-integrated diamond anvil cells

TL;DR

This paper introduces a novel method combining diamond anvil cells with point-contact Andreev reflection spectroscopy to study superconducting thin flakes under pressure, enabling detailed spectroscopic analysis of layered superconductors.

Contribution

It develops a functionalized diamond anvil cell technique for PCAR measurements on thin-flake superconductors under pressure, overcoming previous technical limitations.

Findings

Successfully measured superconducting gaps in iron-selenide flakes under pressure

Demonstrated the method's capability to analyze superconductivity in thin layers

Provided insights into pressure effects on layered superconductor properties

Abstract

Superconductors that can be mechanically exfoliated are an interesting platform for exploring superconducting properties tuned by layer thickness. These layered superconductors are also expected to exhibit sensitivity to applied pressure. While pressure has been demonstrated to be an effective way of tuning bulk superconductors, analogous studies on superconducting thin flakes have been limited due to technical challenges. In particular, spectroscopic measurements under pressure remain insufficiently explored. In this work, we functionalized the diamond anvil cell technique for point-contact Andreev reflection spectroscopy (PCAR) measurement on thin-flake materials under pressure, offering the opportunity to obtain spectroscopic information on superconductivity. To validate the feasibility of this method, we have conducted PCAR measurements on iron-selenide thin flakes to extract temperature-dependent superconducting gap values under ambient and high pressure. Combine with the proven magnetotransport capability, our method provides a conceptually simple tool for a detailed examination of thin-flake superconductors under pressure.