Photo-induced, non-equilibrium spin and charge polarization in quantum rings

Abstract

We investigate the spin-dependent dynamical response of a quantum ring with a spin-orbit interaction upon the application of linearly polarized, picosecond, asymmetric electromagnetic pulses. The oscillations of the generated dipole moment are sensitive to the parity of the occupation number in the ring and to the strength of the spin-orbit coupling. It is shown how the associated emission spectrum can be controlled via the pulse strength or a gate voltage. In addition, we inspect how a static magnetic flux can modify the non-equilibrium dynamics. In presence of the spin-orbit interaction and for a paramagnetic ring, the applied pulse results in a spin-split, non-equilibrium local charge density. The resulting temporal spin polarization is directed perpendicular to the light-pulse polarization axis and oscillates periodically with the frequency of the spin-split charge density. The spin-averaged non-equilibrium charge density possesses a left-right symmetry with respect to the pulse polarization axis. The calculations presented here are applicable to nano-meter rings fabricated in heterojuctions of III-V and II-VI semiconductors containing several hundreds electrons.

24 pages, 8 figures. accepted for publication in Phys. Rev. B

References in corpus (7)

• Persistent current in ballistic mesoscopic rings with Rashba spin-orbit coupling
• Quantum rings as electron spin beam splitters
• Laser-controlled local magnetic field with semiconductor quantum rings
• Non-adiabatic current generation in a finite width semiconductor ring
• Revivals, collapses and magnetic-pulse generation in quantum rings
• Net current generation in a 1D quantum ring at zero magnetic field
• Nonequilibrium charge dynamics of light-driven rings threaded by a magnetic flux