Freire Henrique J P, Egues J Carlos
Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, São Paulo, Brazil.
Phys Rev Lett. 2007 Jul 13;99(2):026801. doi: 10.1103/PhysRevLett.99.026801. Epub 2007 Jul 12.
We use spin-density-functional theory to study recently reported hysteretic magnetoresistance rho(xx) spikes in Mn-based 2D electron gases [Phys. Rev. Lett. 89, 266802 (2002)10.1103/PhysRevLett.89.266802]. 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.
