Publications Details

Quantum Hall ferromagnetic transition in a Ge 2D hole system

Lu, Tzu-Ming L.; Tracy, Lisa A.; Laroche, D.; Huang, S.H.; Chuang, Y.; Su, Y.H.; Li, J.Y.; Liu, C.W.

When two Landau levels are brought into energy degeneracy, interesting phases and phase transitions can occur. For single-layer 2D electrons, a quantum Hall ferromagnetic transition (QHFT) occurs when Landau levels with opposite spins are made degenerate by an in-plane magnetic field, which enhances the Zeeman splitting but keeps the cyclotron energy constant. At the QHFT, the 2D electron system breaks up into magnetic domains with opposite spins, and a resistance spike is observed as electrons move through the domain wall loops. An alternative way to enhance the ratio of Zeeman splitting to the cyclotron energy, which is proportional to m*g*, is to reduce the carrier density (p). Here we report the observation of a QHFT at ν = 2 in a Ge 2D hole system through modulating p without any in-plane magnetic field. We also report the effects of an in-plane magnetic field to this QHFT.