Hysteretic resistance spikes in quantum Hall ferromagnets without domains

TL;DR

This paper uses spin-density-functional theory to explain hysteretic resistance spikes in quantum Hall ferromagnets without involving domain walls, highlighting the role of exchange-correlation effects in phase transitions.

Contribution

It provides a theoretical explanation for hysteretic magnetoresistance spikes in quantum Hall ferromagnets without requiring domain walls, emphasizing the importance of spin-dependent exchange-correlation effects.

Findings

Hysteresis loops in Landau fan diagrams indicate phase transitions.

Hysteretic dips in Hall resistance are predicted.

Exchange-correlation effects stabilize magnetic phases.

Abstract

We use spin-density-functional theory to study recently reported hysteretic magnetoresistance \rho_{xx} spikes in Mn-based 2D electron gases [Jaroszy\'{n}ski et al. Phys. Rev. Lett. (2002)]. We find hysteresis loops in our calculated Landau fan diagrams and total energies signaling quantum-Hall-ferromagnet phase transitions. Spin-dependent exchange-correlation effects are crucial to stabilize the relevant magnetic phases arising from distinct symmetry-broken excited- and ground-state solutions of the Kohn-Sham equations. Besides hysteretic spikes in \rho_{xx}, we predict hysteretic dips in the Hall resistance \rho_{xy}. Our theory, without domain walls, satisfactorily explains the recent data.