Theoretical study of electronic and magnetic properties of diluted magnetic tin telluride

Abstract

We study some aspects of electronic and magnetic properties of diluted magnetic newlinetin telluride in this thesis. Since SnTe belong to IV-VI group of semiconductors and is newlinenormally studied in conjunction with PbTe , we study the electronic structure of both. newlineThe thesis begins with a review of existing literature on the electronic structure of IVVI newlinecompound semiconductors. These include empirical, first-principle and k and#61655;and#61552; newlinemethods. In the latter method, k stands for the electronic wave vector and and#61552; , the newlinerelativistic momentum operator. The k and#61655;and#61552; formulation begins with the effective mass representation in the presence of spin-orbit interaction. In this representation a general newlinewave function is expanded over a complete orthonormal set of Luttinger-Kohn wave newlinefunctions. In the process we derive the k and#61655;and#61552; Hamiltonian. Using a Green s function newlineperturbation theory, we derive an expression for the effective mass which is expressed newlineas a sum of two terms, the free-electron like and the inter-band terms. In the first part of our work we study the effect of the variation of energy gap on newlinethe k and#61655;and#61552; electronic structure of PbTe and SnTe , using a six-level basis at the L point. newlineThe basis functions in both the systems have the same transformation properties. newlineHowever, the basis functions of the band edge states in SnTe are reversed with respect newlineto the same in PbTe . Band dispersions are obtained analytically for a two band model. newline