Field induced superconductivity in a magnetically doped two-dimensional crystal

TL;DR

This study demonstrates magnetic field-induced superconductivity in a two-dimensional LaSb$_2$ crystal doped with Ce impurities, revealing how in-plane magnetic fields can enhance superconductivity by suppressing spin fluctuations.

Contribution

It introduces a novel mechanism for magnetic field-induced superconductivity in a 2D material through impurity and dimensionality engineering.

Findings

Superconducting dome observed at finite magnetic fields.

In-plane magnetic field enhances critical temperature.

Modeling reveals control over magnetic pair-breaking regimes.

Abstract

Magnetic field induced superconductivity is a rare property in nature due to the sensitivity of spin-singlet Cooper pairing to time-reversal symmetry breaking perturbations. However, in rare cases, an interplay between magnetic fields and ions can be engineered to bring about superconductivity at finite fields. Here we use ultra-thin LaSb$_2$ doped with dilute Ce paramagnetic impurities to demonstrate a magnetic field-induced superconducting dome in a two-dimensional crystal. The reduced dimensionality of the structure enables the use of an in-plane magnetic field to dynamically suppress spin fluctuations on the Ce-site, which leads to an anomalous enhancement of the critical temperature with increasing field. By modelling the spin scattering dynamics across the experimental parameter space, we reveal insight into the complex nature of paramagnetic impurities in magnetic fields at low temperature, and how their manipulation can result in the ability to tune between competing magnetic pair-breaking regimes. Realizing this physics in a two-dimensional crystalline setting invites the application of similar approaches to unconventional forms of superconductivity while also highlighting new experimental standards which should be employed when studying ultra-thin materials in general.