Multiple exchange interactions induced by Jahn-Teller distortions in dilute magnetic semiconductors

Abstract

Transition metal impurities in semiconductors exhibit intricate magnetic interactions, usually rationalized via symmetry orbitals assuming an undistorted point symmetry of the host semiconductor. These interactions may then be described via simple rules based on the occupation of these symmetry orbitals. Here we show how the lowering of symmetry via Jahn-Teller-like distortions enriches the variety of possible magnetic interactions, and describe the emerging strong short-range ferromagnetic interactions as concerted multiple exchange interactions caused by an unusual Cr-Cr chemical bond formation in the AlN semiconductor host.