Spin drift-diffusion for two-subband quantum wells

Two-subband quantum Hall effect in parabolic quantum wells

The low-temperature magnetoresistance of parabolic quantum wells displays pronounced minima between integer filling factors. Concomitantly the Hall effect exhibits overshoots and plateaulike features next to well-defined ordinary quantum Hall plateaus. These effects set in with the occupation of the second subband. We discuss our observations in the context of single-particle Landau fan charts ...

Room temperature spin diffusion in (110) GaAs/AlGaAs quantum wells

Transient spin grating experiments are used to investigate the electron spin diffusion in intrinsic (110) GaAs/AlGaAs multiple quantum well at room temperature. The measured spin diffusion length of optically excited electrons is about 4 μm at low spin density. Increasing the carrier density yields both a decrease of the spin relaxation time and the spin diffusion coefficient Ds.

Ambipolar spin diffusion and D’yakonov-Perel’ spin relaxation in GaAs quantum wells

We report theoretical and experimental studies of ambipolar spin diffusion in a semiconductor. A circularly polarized laser pulse is used to excite spin-polarized carriers in a GaAs multiple quantum-well sample at 80 K. Diffusion of electron and spin densities is simultaneously measured using a spatially and temporally resolved pump-probe technique. Two regimes of diffusion for spin-polarized e...

Subband Tunneling and Coulomb Effects in Coupled Quantum Wells

We have solved in space and time the effective-mass nonlinear Schrödinger equation for an electron-hole gas in a semiconductor superlattice. Considering a Coulomb interaction between both electronhole gases and two subbands, we have obtained a time-varying dipole moment in the heterostructure. In this way, we have shown the possibility of having another kind of terahertz electromagnetic radiati...

Optical imaging of trion diffusion and drift in GaAs quantum wells