Dynamic electron spin injection in semiconductor nanostructures

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.

Automated summary

This review article provides an overview of the experimental and theoretical investigation of dynamic electron spin injection in semiconductor nanostructures. The focus is on spin-dependent recombination and spin-dependent tunneling phenomena, which lead to photoluminescence polarization. These phenomena result in fundamentally different dynamic spin polarization compared to the steady state polarization seen in stationary spin injection or s(p)-d exchange interaction in metal/ferromagnetic or semiconductor/ferromagnetic hybrid structures. The study of dynamic spin polarization is receiving increasing attention due to the ability to control the process using external gating and the rich physics of time-dependent processes in semiconductor nanostructures. This article discusses the spin-dependent recombination via deep paramagnetic centers and dynamic spin polarization in hybrid heterostructures, as well as the potential implementation of dynamic spin polarization in spin lasers.