Photoionization absorption and zero-field spin splitting of acceptor-bound magnetic polaron in p-type Hg _1-xMn _xTe single crystals

Temperature-dependent magnetic (2-300 K), DC Hall (10-300 K), and infrared transmission (11.5-300 K) measurements are performed on a series of p-type Hg _1-xMn _xTe (0.12 x 0.26) single crystals in the spin-glass regime. Photoionization absorption (PIA) of acceptor-bound magnetic polarons (acceptor-BMPs) is observed to evolve with temperature, which is better accounted for by the classical oscillator model than by the quantum defect method. At low temperatures, p-type Hg _1-xMn _xTe manifests distinct phenomena of paramagnetic enhancement, negative magnetoresistance, and decrease of the effective binding energy and blueshift of the PIA of the acceptor-BMPs with nearly the same degree as temperature declines. A spin-splitting model is proposed, which can well reproduce the experimentally observed zero-field spin splitting of the acceptor-BMP level at low temperatures and the increase of the spin splitting as temperature drops. The results suggest that the acceptor-BMPs in Hg _1-xMn _xTe may have potential applications in light-driven polaronic memories, tunable far-infrared lasers, and detectors.