Theory of optical conductivity for dilute GaMnAs

Abstract

We construct a semi-microscopic theory, to describe the optical conductivity of GaMnAs in the dilute limit, x = 1%. We construct an effective Hamiltonian that captures inside-impurity band optical transitions as well as transitions between the valence band and the impurity band. All parameters of the Hamiltonian are computed from microscopic variational calculations. We find a metal-insulator transition within the impurity band in the concentration range, x = 0.2 -0.3 for uncompensated and x = 1-3% for compensated samples, in good agreement with the experiments. We find an optical mass m_opt = m_e, which is almost independent of the impurity concentration excepting in the vicinity of the metal-insulator transition, where it reaches values as large as m_opt = 10 m_e. We also reproduce a mid-infrared peak at \hbar ω= 200 meV, which redshifts upon doping, in quantitative agreement with the experiments.

17 pages, 16 figures, submitted to Physical Review B

References in corpus (8)

• Theory of ferromagnetic (III,Mn)V semiconductors
• Impurity Band Conduction in a High Temperature Ferromagnetic Semiconductor
• On the character of states near the Fermi level in (Ga,Mn)As: impurity to valence band crossover
• Curie point singularity in the temperature derivative of resistivity in (Ga,Mn)As
• Ellipsometric study of the Electronic Structure of GaMnAs and LT-GaAs
• Disorder, spin-orbit, and interaction effects in dilute ${\mathrm{Ga}}_{1-x}{\mathrm{Mn}}_x\mathrm{As}$
• Magnetic susceptibility of diluted magnetic semiconductors at low carrier densities
• Optical response of electrons in a random potential

Cited by in corpus (5)

• Controlling Curie temperature in (Ga,Ms)As through location of the Fermi level within the impurity band
• An infrared probe of the insulator-to-metal transition in GaMnAs and GaBeAs
• Ferromagnetism and infrared electrodynamics of Ga${}_{1-x}$Mn${}_x$As}
• Infrared conductivity of hole accumulation and depletion layers in (Ga,Mn)As- and (Ga,Be)As-based electric field-effect devices
• Optical conductivity of Mn doped GaAs