Electronic states and cyclotron resonance in p-type InMnAs and InMnAs/(Al,Ga)Sb at ultrahigh magnetic fields

摘要

We present a theoretical and experimental study on electronic andmagneto-optical properties of p-type paramagnetic InMnAs dilute magneticsemiconductor alloys and ferromagnetic p-type InMnAs/(Al,Ga)Sb thin films inultrahigh (> 100 T) external magnetic fields \textbf{B}. We use an 8 bandPidgeon-Brown model generalized to include the wavevector dependence of theelectronic states along B as well as s-d and p-d exchange interactions withlocalized Mn d-electrons. In paramagnetic p-InMnAs alloys, we compute thespin-dependent electronic structure as a function of Mn doping and examine howthe valence band structure depends on parameters such as the sp-d exchangeinteraction strength and effective masses. The cyclotron resonance (CR) andmagneto-optical properties of InMnAs are computed using Fermi's golden rule. Inaddition to finding strong CR for hole-active polarization in p-type InMnAs, wealso find strong CR for electron-active polarization. The electron-active CR inthe valence bands results from transitions between light and heavy hole Landaulevels and is seen in experiments. In ferromagnetic p-InMnAs/(Al,Ga)Sb, twostrong CR peaks are observed which shift with position and increase in strengthas the Curie temperature is approached from above. This transition takes placewell above the Curie temperature and can be attributed to the increase inmagnetic ordering at low temperatures.