Energy Structure and Quantized Hall Effect of Two-Dimensional Holes

Combined magnetotransport and cyclotron-resonance experiments in a two-dimensional hole system at a modulation-doped GaAs-(AlGa)As heterojunction show that the Kramers degeneracy of the lowest subband is lifted for finite $k$ giving rise to two cyclotron masses ${m_1}^{*}=0.38\mathrm{}{m}_0$ and ${m_2}^{*}=0.60\mathrm{}{m}_0$ at $E_{\mathrm{F}}=2.4\mathrm{}$ meV. The observation of plateaus in ${\rho }_{xy}$ shows that the quantized Hall effect is independent of the details of the host band structure.