Semimagnetic ZnMnSe/CdSe Fractional Monolayer Superlattice as an Injector of Spin‐Polarized Carriers

Abstract

We report on effective injection of spin-oriented carriers from a semimagnetic semiconductor structure to a non-magnetic ZnCdSe/ZnSe quantum well (QW). A short-period ZnMnSe/CdSe fractional monolayer superlattice was used as a spin injector. The carriers are photo-generated in the semimagnetic region, spin-polarized via the effect of giant Zeeman splitting and then injected into the non-magnetic QW. The spin injection efficiency was estimated by circular polarization measurements of recombination emission from the QW. The maximal detected degree of the spin polarization is about 25%.In the past few years there has been growing interest in a new concept of electronic devices for data storage and processing -the so-called "spintronics". The basic idea of spintronics is the manipulation by electron spin rather than by electric charge [1]. The design of effective injectors of spin-oriented carriers is necessary for all types of spin devices. A perfect spin injector must operate without application of external magnetic field and at ambient temperature, but despite the significant efforts of numerous research teams this goal has not been achieved so far.Until recently, the most successful realizations of the injection of spin-polarized electrons have employed diluted magnetic semiconductors (DMS) [2][3][4][5]. Both II-VI semimagnetic semiconductors [2-4] and III-V ferromagnetic semiconductors [5] were used to demonstrate injection of spins into either a bulk non-magnetic II-VI layer [2] or a non-magnetic III-V quantum well (QW) structure [3][4][5]. The best achieved values of operation temperature at still reasonable injection efficiency (about 10%) are 6 K for a ferromagnetic p-GaMnAs injector [5] and about 35 K for a BeMnZnSe injector [3]. So the problem of spin injection into semiconductor structures still remains very topical. The further progress in this field is closely connected with fundamental studies of spin transport and relaxation as well as with the search of novel spin injecting materials and structures.In the present paper we propose and study a spin injector based on a II-VI quantum heterostructure -a CdSe/ZnMnSe semimagnetic fractional monolayer (FM) superlattice (SL). For this purpose we have designed a sample including the DMS FM SL with an attached non-magnetic ZnCdSe QW. Previously, similar structures with a non-mag-1 ) Corresponding author;