Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 3: Spintronik I

HL 3.8: Talk

Friday, March 4, 2005, 12:30–12:45, TU P164

Spin Transport by Surface Acoustic Waves in (110) GaAs Quantum Wells — •Yang Guang, Fernando Iikawa, Rudolph Hey, and Paulo V. Santos — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany

The manipulation and transport of spins are critical steps towards the realization of novel, functional devices for information processing, quantum computing, and quantum cryptography. Recently, we have demonstrated that the piezoelectric field induced by a surface acoustic wave (SAW) can be applied to increase the lifetime of photogenerated spins and transport them in semiconductor quantum wells (QWs) [1]. One of the limitation of the SAW-induced spin transport is the rather slow acoustic propagation velocity, which requires very long spin lifetimes for large (i.e., several tens of µm) transport lengths. In this work, we demonstrate spin transport lengths approaching 20 µm in GaAs/(Al,Ga)As QWs grown along the [110] direction. The longer lifetimes and transport lengths under the SAW fields are attributed to the simultaneous quenching of the excitonic [2] and D’yakonov-Perel (DP) spin relaxation mechanisms in (110) QWs [3]. We further show that the spins can be manipulated during transport by applying a magnetic field perpendicular to the carrier propagation direction, thus opening the way for applications in quantum information processing.

[1] T. Sogawa et al., Phys. Rev. Lett. 87, 276601 (2001)

[2] M. Z. Maialle et al., Phys. Rev. B47, 15776 (1993)

[3] Y. Ohno et al., Phys. Rev. Lett. 83, 4196 (1999)