Effects of chiral helimagnets on vortex states in a superconductor

TL;DR

This study explores how chiral helimagnets influence vortex configurations in superconductors, revealing the formation and evolution of vortex structures under varying external and magnetic fields using Ginzburg-Landau modeling.

Contribution

It introduces a model incorporating spatially oscillating magnetic fields from chiral helimagnets to analyze vortex states in superconductor bilayers.

Findings

Down-vortices diminish with increasing external magnetic field.

Up-vortices form ordered lattice structures at high fields.

Chiral helimagnets significantly alter vortex arrangements.

Abstract

We have investigated vortex states in chiral helimagnet/superconductor bilayer systems under an applied external magnetic field Happl, using the Ginzburg-Landau equations. Effect of the chiral helimagnet on the superconductor is taken as a magnetic field HCHM, which is perpendicular to the superconductor and oscillates spatially. For Happl = 0 and weak HCHM, there appear pairs of up-and down-vortices. Increasing Happl, down-vortices gradually disappear, and number of up-vortices increases in the large magnetic field region. Then, up-vortices form parallel, triangular, or square structures.