Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor

TL;DR

This study demonstrates that spin-polarized currents can switch magnetic order and suppress superconductivity in an iron-based superconductor, revealing a new method to control these states via tunneling currents.

Contribution

The paper introduces a novel mechanism for controlling magnetism and superconductivity in iron-based superconductors using spin-polarized tunneling currents, not achievable by thermal means.

Findings

Spin-polarized current induces a $C_4$ magnetic order in Sr$_2$VO$_3$FeAs.

The induced magnetic order suppresses superconductivity.

Thermal agitation erases the magnetic order beyond the bulk spin temperature.

Abstract

We have explored a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single crystal Sr$_2$VO$_3$FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a non-trivial $C_4$ (2$\times$2) order, not achievable by thermal excitation with unpolarized current. Our tunneling spectroscopy study shows that the induced $C_4$ (2$\times$2) order has characteristics of plaquette antiferromagnetic order in Fe layer and strongly suppressed superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the $C_4$ state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.