No abstract

Integration of magnetism into semiconductor electronics would facilitate an all-in-one-chip computer. Ferromagnet/bulk semiconductor hybrids have been, so far, mainly considered as key devices to read out the ferromagnetism by means of spin injection. Here we demonstrate that a mn-based ferromagnetic layer acts as an orientation-dependent separator for carrier spins confined in a semiconductor quantum well that is set apart from the ferromagnet by a barrier only a few nanometers thick. By this spin-separation effect, a non-equilibrium electronspin polarization is accumulated in the quantum well due to spin-dependent electron transfer to the ferromagnet. The significant advance of this hybrid design is that the excellent optical properties of the quantum well are maintained. This opens up the possibility of optical readout of the ferromagnet's magnetization and control of the non-equilibrium spin polarization in non-magnetic quantum wells.

No abstract

No abstract

No abstract

Optical single dot studies in wide-band gap diluted magnetic CdSe/ZnMnSe quantum dots have been performed. Due to the sample design, the photoluminescence energy of the quantum dot signal is energetically below the internal Mn2+ transition, resulting in high quantum efficiencies comparable to nonmagnetic CdSe/ZnSe quantum dots. Magnetic-field- and temperature-dependent measurements on individual dots clearly demonstrate the exchange interaction between single excitons and individual Mn2+ ions, resulting in a giant Zeeman effect and a formation of quasi-zero-dimensional magnetic polarons.

Light-emitting device heterostructures with a δ⟨Mn⟩-doped layer inserted between the Schottky contact and near-surface InGaAs/GaAs quantum well (QW) have been fabricated. The δ⟨Mn⟩-doped layer facilitates hole tunnelling from the Schottky contact to the QW and impedes that of QW electrons in the opposite direction. It leads to a highly enhanced electroluminescence signal from the InGaAs QW. An effective p–d exchange interaction of holes with magnetic moments of Mn ions is found to strongly enhance the effective hole g-factor and the circular polarization of the low (∼2 K) temperature emission up to 20% in magnetic fields of 1–2 T.

Time-resolved and cw photoluminescence ͑PL͒ spectra are studied in type-II ZnSe/BeTe multiple quantum wells. Samples with nonequivalent interfaces exhibit a strong in-plane linear polarization of the PL along a ͗110͘ axis. The polarization is stable with respect to an increase in the excitation intensity by many orders of magnitude, to a raising of the temperature up to 300 K and not influenced by applied electric or magnetic fields. The experimental data are discussed in the framework of a tight-binding model taking into account a type-II band alignment and lack of common atom in the ZnSe/BeTe heterosystem.