Magnetic skyrmions and their lattices in triplet superconductors

TL;DR

This paper classifies topological solutions in SO(3) symmetric Ginzburg-Landau theory, discovering magnetic skyrmions with unique properties, their lattice formations, and experimental relevance in certain superconductors.

Contribution

It provides a complete topological classification, identifies new magnetic skyrmion solutions, and explores their lattice structures and experimental implications.

Findings

Magnetic skyrmions carry two units of flux without singular cores.

Skyrmions form stable triangular lattices due to repulsive interactions.

The magnetic induction near Hc1 matches experimental data on UPt3.

Abstract

Complete topological classification of solutions in SO(3) symmetric Ginzburg-Landau free energy has been performed and a new class of solutions in weak external magnetic field carrying two units of magnetic flux has been identified. These solutions, magnetic skyrmions, do not have singular core like Abrikosov vortices and at low magnetic field become lighter for strongly type II superconductors. As a consequence, the lower critical magnetic field Hc1 is reduced by a factor of log(kappa). Magnetic skyrmions repel each other as 1/r at distances much larger then magnetic penetration depth forming relatively robust triangular lattice. Magnetic induction near Hc1 increases gradually as (H-Hc1)^2. This agrees very well with experiments on heavy fermion superconductor UPt3. Newly discovered Ru based compounds Sr2RuO4 and Sr2YRu(1-x)Cu(x)O6 are other possible candidates to possess skyrmion lattices. Deviations from exact SO(3) symmetry are also studied.