Magnetism versus band-gap relationship in diluted magnetic semiconductors: megatom impurity behavior of the magnetic dopant complexes
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Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
Antonis N Andriotis1, Madhu Menon2
1Institute of Electronic Structure and Laser, FORTH, PO Box 1527, 71110 Heraklio, Crete, Greece.
Abstract:
An analysis ofab initionumerical results obtained for the total energy of diluted magnetic semiconductors (DMSs) doped with dopant formations of various structural and spin conformations consisting of 2-4 3D transition metal (TM atoms) has revealed that a dopant formation acts as large impurity atom i.e., as amegatom, in a reverse analogy to the process of the adsorption ofsp-atoms onto metallic surfaces. As a result, thed-orbitals of the magnetic dopant formation (themegatom) become hybridized with thesp-bands of the host anions thus creating a number of impurity states which are reflected in the changes of the band gap of the DMS establishing an implicit relationship between the band gap and magnetism. Additional findings also indicate that: (i) the total magnetic momentMtot(α)and the band gapegap(α)which characterize a DMS with a dopant formation in spin conformation (α) do not vary independently from each other but instead form one composite system parameter. (ii) The per dopant-pair magnetic interactions in dopant formations consisting of more than two dopants are smaller than those obtained for an isolated dopant-pair. These are demonstrated with results obtained for GaN doped with 3D-TM dopant formations.
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