Far-infrared magnetoabsorption studies of zero-gap Hg1-xMnxSe crystals.

Abstract

The results of magnetotransmission measurements performed on ${\mathrm{Hg}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se crystals (0.021\ensuremath{\le}x\ensuremath{\le}0.05) at different temperatures are presented. The investigated materials have an inverted band structure (like HgSe). Most of the observed features are explained by transitions between conduction-band Landau levels, described by the Pidgeon-Brown model extended to include exchange interaction. The obtained values of the interaction gap ${\mathit{E}}_{0}$ and matrix element P complement results obtained from transport and interband magnetotransmission measurements, and show a nonlinear behavior of ${\mathit{E}}_{0}$ vs Mn composition x and a strong nonmonotonic dependence of P on x. The temperature dependence of Landau-level energies at low temperatures (between 2 and 8 K) is due to the changes of magnetization with temperature. In addition to spin and combined resonances, transitions allowed by warping and/or inversion asymmetry such as the second and third cyclotron harmonics are observed. The transitions, which could not be explained by transitions between Landau levels, are attributed to transitions from an impurity level (probably an ionized acceptor state) resonant with the conduction band. The zero-field energy of the level is estimated to be 3.8 meV above the top of the valence band.