Distance Dependence of the Mn--Mn Exchange Interaction in IV--VI Semimagnetic Semiconductors

A. Łusakowski and M. Górska Institute of Physics, Polish Academy of Sciences al. Lotników 32/46, 02-668 Warszawa, Poland

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In the present paper we calculate the exchange interaction between two manganese ions in IV--VI semiconductors with the rocksalt structure. The method of calculations is based on the fourth order perturbation theory with respect to hybridization between band states and localized d orbitals of Mn ions. This hybridization is described by three Harrison integrals: V pdσ , V pdπ , and V sdσ . The band states of IV--VI semiconductor are obtained from the semiempirical tight binding model built from s and p orbitals of cations and anions. The resulting exchange term in the Hamiltonian is of the form -∑ i,j=xyz J ij 1 i S 2 j , however nondiagonal terms of the exchange integral tensor J i\ne=j are very small. The dependence of J ij on the Mn--Mn distance is non-monotonic. We also discuss the influence of the local crystal deformations on the exchange integral.

DOI: 10.12693/APhysPolA.103.659 PACS numbers: 71.70.Gm, 75.30.Hx