Bound states and scattering of magnons on a superconducting vortex in ferromagnet-superconductor heterostructures

TL;DR

This paper investigates how a superconducting vortex influences magnon behavior in a ferromagnet-superconductor heterostructure, revealing vortex-induced magnon localization, skew scattering, and the dependence on material parameters.

Contribution

It introduces a detailed analysis of magnon spectra and scattering in the presence of a vortex using the Bogolubov-de Gennes framework, highlighting vortex-induced effects.

Findings

Magnon states are localized by the vortex similarly to electron bound states.

The number of localized magnon states depends on ferromagnetic material parameters.

Vortices cause skew scattering of magnons, affecting their transport properties.

Abstract

We study the magnon spectrum in a thin ferromagnetic-superconductor heterostructure in the presence of a single superconducting vortex. We employ the Bogolubov-de Gennes Hamiltonian which describes the magnons in the presence of the stray magnetic field and the non-uniform magnetic texture induced by the vortex. We find that the vortex localizes magnon states approximately in the same way as a charge center produces electron bound states due to screened Coulomb interaction in the two-dimensional electron gas. The number of these localized states is substantially determined by the material parameters of the ferromagnetic film only. We solve the scattering problem for an incident plane spin wave and compute the total and transport cross sections. We demonstrate that the vortex-induced non-uniform magnetic texture in chiral ferromagnetic film produces a skew scattering of magnons. We explore the peculiarities of the quantum scattering problem that correspond to orbiting in the classical limit.