Ellipsometric study of the electronic structure ofGa1−xMnxAsand low-temperature

Kenneth S. Burch

¹

,

J. W. W. Stephens

²

,

Roland Kawakami

³

et al.

Abstract

We have measured the optical constants of Ga 1−x Mn x As from 0.62 eV to 6 eV, using spectroscopic ellipsometry. The second derivatives of the dielectric function are examined through a critical point analysis. The E 1 critical point shifts to higher energies with increased doping of Mn, while all other critical points appear unaffected. The evolution of the critical points results from the interplay between band gap renormalization from ionized impurities and sp-d hybridization of the Mn induced impurity band and GaAs valence and conductions bands.

Ferromagnetism and infrared electrodynamics of Ga1−xMnxAs

“…In this way, we construct a KK consistent model of σ(ω) over the entire experimental range. Modeling the data over such a large experimental frequency range assures a high degree of confidence in the uniqueness and accuracy of each experimental fit 40,41 . We focus on the real part of the conductivity spectrum, σ 1 (ω), describing the dissipative processes in the system.…”

Disorder, spin-orbit, and interaction effects in diluteGa1−xMnxAs

“…Indeed, this scenario seems to be supported by many experiments. 9,10,11,12,13,14,15,16 Fig . 9 shows the dependence of the DOS on MC time for fixed x.…”

Ferromagnetic semiconductors: moving beyond (Ga,Mn)As

“…Disorder is critically important, and ferromagnetism, when it occurs, is more fragile. Theorists have also used model approaches with varying degrees of realism to look at this regime, which cannot be described by the simple mean-field theory, accounting for the effects of disorder and localization, 68,69,70,71,72 the possible role of impurity band formation, 73,74 and the role of specific defects. 75,76 This combination of several different approaches has been useful in building an understanding across the entire accessible range of electrical and magnetic doping.…”