Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 49: Poster II

HL 49.45: Poster

Thursday, March 27, 2003, 16:30–19:00, HSZ/P2

Spin-sensitive bleaching: a microscopic approach — •Christian Lechner and Ulrich Rössler — Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany

In recent experiments on p-type quantum well (QW) structures a polarization-dependent saturation of far-infrared absorption was discovered [1]. These experiments, based on the photogalvanic effect [2], have been analyzed with a phenomenological theory, which accounts for spin-sensitive relaxation.

We present a microscopic theory for the saturation of the absorption in dependence on the light polarization. It is derived from the extended semiconductor Bloch equations, including spin and polarization degrees of Freedom [3], which are adapted to far-infrared excitation of p-doped QW. Employing Hartree-Fock truncation and assuming finite life-times of the single-particle states, we find the equations of motion for the spin-dependent density matrix of the hole system. Assuming quasi-equilibrium we can solve these equations to derive the nonlinear response to the FIR excitation with linear and circular polarization. The results are compared with the phenomenological theory presented in [1].

[1] S.D. Ganichev et al., Phys. Rev. Lett. 88, 057401 (2002)

[2] S.D. Ganichev et al., Appl. Phys. Lett. 77, 3146 (2000)

[3] U. Rössler, phys. stat. sol.(b) 234, 385 (2002)