INTERBAND TRANSITION STRENGTH AND MAGNETOABSORPTION SPECTRUM IN TYPE-I SUPERLATTICES IN INPLANE MAGNETIC-FIELDS

Using a simplified parabolic band model approach within the framework of the envelope function approximation, the influence of in-plane magn etic fields on the electronic and optical properties of type-I superla ttices is studied. The results are in qualitative agreement with exper imental facts previously reported, as well as with previous theoretica l results obtained using more elaborated and toilsome methods. Further more, this approach allows to advance, in a great extent, in the analy tical treatment of interband transitions, leading straightforwardly to some general conclusions. The not well understood case of high magnet ic field effects (magnetic length comparable with the superlattice per iod) is studied in detail. There strong variations of the interband tr ansition strengths as function of the cyclotron orbit center position are found, a fact which is directly connected with the broadening and final saturation of the magneto-absorption spectrum with increasing fi elds. A consistent explanation of such strong variations is given in t erms of magnetic subband mixing.