J. A. Brum

Theory of magnetic anisotropy in III 1 − x Mn x V ferromagnets

We present a theory of magnetic anisotropy in

Micro-photoluminescence of self-assembled quantum dots in the presence of an electron gas

{\mathrm{III}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{V}

Effects of an electron gas on the negative trion in semiconductor quantum wells

-diluted magnetic semiconductors with carrier-induced ferromagnetism. The theory is based on four- and six-band envelope function models for the valence-band holes and a mean-field treatment of their exchange interactions with

The role of finite hole mass in the negatively charged exciton in two dimensions

{\mathrm{Mn}}^{++}

Optical detection of charge redistribution in a δ modulation-doped GaAs–AlxGa1−xAs heterojunction

ions. We find that easy-axis reorientations can occur as a function of temperature, carrier density p, and strain. The magnetic anisotropy in strain-free samples is predicted to have a

Optical properties of type-I and II quantum dots

{p}^{5/3}

Negatively charged donors in semiconductor quantum wells in the presence of longitudinal magnetic and electric fields

hole-density dependence at small p, a

Binding Energy of Negatively Charged Exciton in a Semiconductor Quantum Well: The Role of Interface Defects

{p}^{\ensuremath{-}1}

Chemical-bond approach to the dielectric constant of Se and Te

dependence at large p, and remarkably large values at intermediate densities. An explicit expression, valid at small p, is given for the uniaxial contribution to the magnetic anisotropy due to unrelaxed epitaxial growth lattice-matching strains. Results of our numerical simulations are in agreement with magnetic anisotropy measurements on samples with both compressive and tensile strains. We predict that decreasing the hole density in current samples will lower the ferromagnetic transition temperature, but will increase the magnetic anisotropy energy and the coercivity.

Negative Trion Binding Energy in Semiconductor Quantum Wells: Effects of Structural Confinement and Longitudinal Electric Field

Abstract InGaAs/GaAs self-assembled quantum dots in the presence of a two-dimensional electron gas were studied by micro-photoluminescence. Several sharp optical emission lines attributed to individual quantum dots were observed. These lines exhibit a blue shift and a broadening as the electron gas density is increased. We discuss the origin of the blue shift considering the variation of the built-in electric field in the asymmetric geometry of the dots. The observed broadening of the quantum dot emission lines is an indication of coupling between the two-dimensional electron gas and the electrons in the quantum dot.