MAGNETOOPTICAL PROPERTIES OF DILUTED MAGNETIC PBSE PB1-XMNXSE SUPERLATTICES/

PbSe/Pb1-xMnxSe superlattices (x<0.02, periods: <40 nm) were grown by molecular-beam epitaxy on (111) oriented substrates. They were investi gated by interband absorption in Faraday geometry (B parallel to k par allel to[111]) and by coherent anti-Stokes Raman scattering in the mid -infrared range with B parallel to[1(1) over bar0$] (i.e., in the plan e of the layers) up to 7 T at temperatures in the range of 1.7-20 K. T he latter method yields precise information on the spin splittings of valence and conduction bands as a function of applied magnetic field a nd of temperature. The experimental results yield a staggered band ali gnment with the conduction-band edge of the wider gap Pb1-xMnxSe layer s below that of the PbSe layers. A detailed theoretical analysis is ma de on the basis of a four-band envelope-function approximation taking into account the exchange interaction between the localized electrons of the half-filled Mn2+ 3d shell and the mobile carriers in mean-field approximation. Energy eigenstates and eigenfunctions have been calcul ated as well as interband selection rules. For the Voigt geometry, whe re the electric and magnetic motions are not decoupled, the center coo rdinate of the Landau orbits remains a good quantum number, albeit tha t the corresponding degeneracy of eigenstates is lifted. The dependenc e of the eigenstates and of the g values on the value of the center co ordinate along the superlattice growth direction is investigated in de tail. A normalized conduction-band offset Delta E(c)/Delta E(g) of -0. 4 is obtained.