Magneto-optical probe of quantum Hall states in a wide parabolic well modulated by random potential

Abstract

Polarized photoluminescence from weakly coupled random multiple well quasi-three-dimensional electron system is studied in the regime of the integer quantum Hall effect. Two quantum Hall ferromagnetic ground states assigned to the uncorrelated miniband quantum Hall state and to the spontaneous interwell phase coherent dimer quantum Hall state are observed. Photoluminescence associated with these states exhibits features caused by finite-size skyrmions: dramatic reduction of the electron spin polarization when the magnetic field is increased past the filling factor ν = 1. The effective skyrmion size is larger than in two-dimensional electron systems.

Excitonic spin-splitting in quantum wells with a tilted magnetic field

“…The sample was grown by molecular beam epitaxy and consists of intentionally disordered (Al x Ga x−1 As) n (Al y Ga y−1 As) m , weakly coupled MQWs embedded in a wide parabolic quantum well, where n and m are the thicknesses of the wells and the barriers expressed in units of monolayers (MLs) respectively. The disorder, which increases charge modulation, [10] is introduced by a deliberate random variation in the well thickness n around the nominal value n = 65 ML, while the quantum wells are separated by fixed AlGaAs barriers with m = 15 ML. Details of the determination of disorder strength and sample growth were published in [9,10].…”

“…The disorder, which increases charge modulation, [10] is introduced by a deliberate random variation in the well thickness n around the nominal value n = 65 ML, while the quantum wells are separated by fixed AlGaAs barriers with m = 15 ML. Details of the determination of disorder strength and sample growth were published in [9,10]. The electrons are supplied by Si dopants set back 12.4 nm from the well edges in Si-doped sheets on both sides of the MQW structure.…”

Optically Induced Nuclear Spin Polarization in the Quantum Hall Regime: The Effect of Electron Spin Polarization through Exciton and Trion Excitations

“…To know the electron spin polarization P e , the optical dichroism calculated from the trion absorption is available [1]. Although we cannot measure the absorption of our sample, the PL polarization P L has a contribution of P e and has been utilized to extract the P e characteristics [25,26]. We develop the P e estimation from P L .…”

Spectroscopic evidence of quantum Hall interlayer tunneling gap collapse caused by tilted magnetic field in a GaAs/AlGaAs triple quantum well

“…It is worth mentioning that the effects of electron correlations were also observed in a high-mobility weakly coupled MQW embedded in a wide AlGaAs parabolic well where the quantum transition manifesting itself in a redistribution of the electron density over the quantum wells was found in Refs. [19][20][21]. An important result of electron correlations in MQW is the collapse of the QH tunneling gaps, which has been predicted to occur in coupled QH bilayers in tilted magnetic fields B in Ref.…”