Dynamic electron spin injection in semiconductor nanostructures

Abstract

We review experimental and theoretical study of dynamic electron spin injection in semiconductor nanostructures. The review is focused on spin-dependent recombination and spin-dependent tunneling phenomena leading to a photoluminescence polarization. These phenomena lead to fundamentally different dynamic spin polarization of the electrons in contrast to the polarization in a steady state under, stationary spin injection or in the case of s(p)–d exchange interaction in typical metal/ferromagnetic or semiconductor/ferromagnetic hybrid structures. Growing attention to the mechanisms leading to dynamic spin polarization is the result of (i) the possibility to precisely control the process by means of external gating and (ii) rich and still not well understood physics of the time dependent processes in semiconductor nanostructures. Moreover, non stationary processes allow to highlight the role of Coulomb correlations in the formation of carriers spin polarization. The described physics of dynamic polarization is expected in a variety of systems including semiconductor-QW based heterostructures, nanoplatelets and novel 2D materials. In the first part of the review the spin-dependent recombination via deep paramagnetic centers is discussed, which allows to obtain an unusually high spin polarization for carriers in nonmagnetic semiconductor alloys. The second part deals with the dynamic spin polarization in hybrid heterostructures semiconductor quantum well — magnetic dopant layer. Finally, possible implementation of the dynamic spin polarization in spin lasers is addressed. We also shortly discuss such perspective area as spin injection in microwave and terahertz frequency. We conclude with some open questions and other promising implementation of discussed effect which we consider very important for further development of spintronics.