Spontaneous Spin Splitting Research Articles

Quenching of asymmetry-induced spontaneous spin splitting inp-type quantum wells by an applied magnetic field

The spin splitting in the valence band in an ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}/{\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{y}{\mathrm{P}}_{1\ensuremath{-}y}$ quantum well is investigated theoretically using a $6\ifmmode\times\else\texttimes\fi{}6$ Luttinger-Kohn Hamiltonian. We compare the Landau levels in a perpendicular magnetic field with the corresponding results for the subband dispersions. It is shown that the asymmetry of the quantum well has a very small impact on the Landau level splitting except for quite small magnetic fields. This is in sharp contrast to the subbands in the absence of a magnetic field. It is suggested that the standard interpretation of Shubnikov--de Haas experiments in terms of hole spin subband populations requires a closer analysis.

Spontaneous splitting of ferromagnetic (Ga, Mn)As valence band observed by resonant tunneling spectroscopy

Current–voltage characteristics of AlAs/GaAs/AlAs double barrier resonant tunneling diodes with ferromagnetic p-type (Ga, Mn)As on one side and p-type GaAs on the other have been studied. A series of resonant peaks have been observed in both polarities, i.e., injecting holes from p-type GaAs and from (Ga, Mn)As. When holes are injected from the (Ga, Mn)As side, spontaneous resonant peak splitting has been observed below the ferromagnetic transition temperature of (Ga, Mn)As without magnetic field. The temperature dependence of the splitting is explained by the the spontaneous spin splitting in the valence band of ferromagnetic (Ga, Mn)As.