Spontaneous Transition to a Correlated Phase of Skyrmions Observed in Real Space

TL;DR

This study uses photoluminescence microscopy to observe a spontaneous phase transition to skyrmions in a 2D electron system near the quantum Hall state, revealing real-space spin domain structures and hysteresis effects.

Contribution

It provides the first real-space imaging of skyrmion phase domains and identifies the transition as protected by an energy gap involving Zeeman energy.

Findings

Discontinuity in electron and nuclear spin polarization at transition

Real-space imaging of coexisting spin phase domains

Hysteresis observed in domain formation

Abstract

We conduct photoluminescence microscopy that is sensitive to both electron and nuclear spin polarization to investigate the changes that occur in the magnetic ordering in the vicinity of the first integer quantum Hall state in a GaAs 2D electron system (2DES). We observe a discontinuity in the electron spin polarization and nuclear spin longitudinal relaxation time which heralds a spontaneous transition to a phase of magnetic skyrmions. We image in real space the spin phase domains that coexist at this transition, and observe hysteresis in their formation as a function of the 2DES's chemical potential. Based on measurements in a tilted magnetic field orientation, we found that the transition is protected by an energy gap containing the Zeeman energy, and conclude that the skyrmions here have formed as an ensemble.