# Quantum skyrmions in frustrated ferromagnets

## TL;DR

This paper develops a quantum theory for skyrmions in frustrated ferromagnets, revealing their stable many-magnon bound states, unusual tunneling properties, and unique responses to external forces.

## Contribution

It introduces a quantum description of skyrmions in a frustrated quantum magnet, including a phenomenological Schrödinger equation and analysis of their quantum properties.

## Key findings

- Quantum skyrmions are stable many-magnon bound states.
- Their bandwidth is exponentially small due to tunneling.
- They exhibit unconventional motion under external forces.

## Abstract

We develop a quantum theory of magnetic skyrmions and antiskyrmions in a spin-1/2 Heisenberg magnet with frustrating next-nearest neighbor interactions. Using exact diagonalization we show numerically that a quantum skyrmion exists as a stable many-magnon bound state and investigate its quantum numbers. We then derive a phenomenological Schr\"odinger equation for the quantum skyrmion and its internal degrees of freedom. We find that quantum skyrmions have highly unusual properties. Their bandwidth is exponentially small and arises from tunneling processes between skyrmion and antiskyrmion. The bandstructure changes both qualitatively and quantitatively when a single spin is added or removed from the quantum skyrmion, reflecting a locking of angular momentum and spin quantum numbers characteristic for skyrmions. Additionally, while for weak forces the quantum skyrmion is accelerated parallel to the force, it moves in a perpendicular direction for stronger fields.