Rotation of the magnetic vortex lattice in Ru7B3 driven by the effects of broken time-reversal and inversion symmetry

TL;DR

This study reports a hysteretic reorientation of the magnetic vortex lattice in the noncentrosymmetric superconductor Ru7B3, driven by magnetic field changes and linked to broken time-reversal and inversion symmetries.

Contribution

The paper introduces a Ginzburg-Landau model explaining vortex lattice rotation caused by broken symmetries and spontaneous magnetic fields in Ru7B3.

Findings

Continuous vortex lattice rotation with hysteresis observed.

Vortex lattice orientation linked to time-reversal symmetry breaking.

Model shows coupling of broken symmetries causes vortex rotation.

Abstract

We observe a hysteretic reorientation of the magnetic vortex lattice in the noncentrosymmetric superconductor Ru7B3, with the change in orientation driven by altering magnetic field below Tc. Normally a vortex lattice chooses either a single or degenerate set of orientations with respect to a crystal lattice at any given field or temperature, a behavior well described by prevailing phenomenological and microscopic theories. Here, in the absence of any typical VL structural transition, we observe a continuous rotation of the vortex lattice which exhibits a pronounced hysteresis and is driven by a change in magnetic field. We propose that this rotation is related to the spontaneous magnetic fields present in the superconducting phase, which are evidenced by the observation of time-reversal symmetry breaking, and the physics of broken inversion symmetry. Finally, we develop a model from the Ginzburg-Landau approach which shows that the coupling of these to the vortex lattice orientation can result in the rotation we observe.