STUDY OF FERROMAGNETISM IN DILUTED MAGNETIC SEMICONDUCTOR CaAs

Calcium Arsenide is a promising ferromagnetic material if a zinc-blende crystal structure is assumed. The origin of its ferromagnetic order depends on the appearance of a flat arsenic p- electron band at the Fermi energy in the fully ordered compound. This is in contrast to most other DMS's like Cromium Arsenide and Manganese-doped Gallium Arsenide where they possess magnetic moments or magnetic transition metal impurities which are inserted into a host crystal. The strange ferromagnetic order in zb-Calcium Arsenide is favored by large lattice constants and empty 3d orbitals that are present due to the Ca cations. The mechanism of magnetism has been confirmed by studying fcc-As with two electrons added and by this it is considered that the role of Ca is to provide two electrons with the hypothetical crystal and to adjust the atomic distances between the As atoms. The slightly hybridized p states of As atom interact with each other via the exchange interaction. Finally, the study of ferromagnetism in DMSs is relevant for quantum computing and quantum communications.

Autorentext

Merhawi obtained his Bachelor's & Master's degrees in Physics in 2005 & 2007 from Haromaya & Addis Ababa Universities, respectively. He has worked as a lecturer of physics in Aksum University since 2007. Recently, he has co-authored a few physics teaching modules for the undergraduate students. His research interest lies in DMS & Optics.