Strain-Switchable Field-Induced Superconductivity

TL;DR

This paper reports the discovery of field-induced superconductivity at 9K in a ferromagnetic superconductor, achieved through stress and magnetic field tuning, revealing an electromagnetic mechanism behind this rare phenomenon.

Contribution

It demonstrates record-high temperature field-induced superconductivity in Eu(Fe$_{0.88}$Co$_{0.12}$)$_{2}$As$_{2}$ and elucidates the independent roles of stress and magnetic field in tuning superconductivity.

Findings

Superconductivity achieved at 9K in Eu(Fe$_{0.88}$Co$_{0.12}$)$_{2}$As$_{2}$.

Stress and magnetic field independently tune the superconducting state.

Electromagnetic mechanism confirmed by DFT and Eu dipole field analysis.

Abstract

Field-induced superconductivity is a rare phenomenon where an applied magnetic field enhances or induces superconductivity. This fascinating effect arises from a complex interplay between magnetism and superconductivity, and it offers the tantalizing technological possibility of an infinite magnetoresistance superconducting spin valve. Here, we demonstrate field-induced superconductivity at a record-high temperature of T=9K in two samples of the ferromagnetic superconductor Eu(Fe$_{0.88}$Co$_{0.12}$)$_{2}$As$_{2}$. We combine tunable uniaxial stress and applied magnetic field to shift the temperature range of the zero-resistance state between 4K and 10K. We use x-ray diffraction and spectroscopy measurements under stress and field to demonstrate that stress tuning of the nematic order and field tuning of the ferromagnetism act as independent tuning knobs of the superconductivity. Finally, DFT calculations and analysis of the Eu dipole field reveal the electromagnetic mechanism of the field-induced superconductivity.