Abstract
The electronic and magnetic properties of transition metal (Mn and Cr) doped Aluminium Nitride (AlN) in the wurtzite structure is studied using the single impurity Anderson model (SIAM) extended to semiconductors by Haldane. An equation of motion method based on Green’s function was used to obtain the effective spin decomposed impurity levels. The calculated electronic density of states of Mn and Cr valence orbitals exhibit half metallic properties when the impurity is strongly coupled to the host. The effect of the Coulomb correlation and orbital hybridization on the formation of a localized moment in such systems is investigated. Magnetic impurities are often responsible for the inelastic scattering of conduction electrons. For a configuration averaged random ensemble of impurities, initially non-polarized host band develops a small moment presumably due to the potential scattering.
Highlights
INTRODUCTIONThe ferromagnetism arising due to magnetic correlations of a transition metal (TM) impurity in a III-V semiconductor host, which in other words are called diluted magnetic semiconductors (DMSs), has received much attention in the field of spintronics. Among the III-V semiconductors, Aluminium Nitride (AlN) has the largest band gap experimentally determined to be 6.2 eV with many preferred properties such as high thermal stability, good thermal conductivity, low compressibility etc. AlN doped with TM atoms with a partially filled d orbital viz. Manganese, Chromium, Iron, Vanadium etc. belongs to this interesting class of semiconductors, that various studies has reported as good candidates for spintronic applications often owing to their half metallic properties
Aluminium Nitride (AlN) doped with transition metal (TM) atoms with a partially filled d orbital viz. Manganese, Chromium, Iron, Vanadium etc. belongs to this interesting class of semiconductors, that various studies has reported as good candidates for spintronic applications often owing to their half metallic properties
We have investigated the electronic structure of the impurity and their magnetic moments for various values of the parameters that describe the single impurity Anderson model (SIAM) to obtain the conditions for local moment formation
Summary
The ferromagnetism arising due to magnetic correlations of a transition metal (TM) impurity in a III-V semiconductor host, which in other words are called diluted magnetic semiconductors (DMSs), has received much attention in the field of spintronics. Among the III-V semiconductors, Aluminium Nitride (AlN) has the largest band gap experimentally determined to be 6.2 eV with many preferred properties such as high thermal stability, good thermal conductivity, low compressibility etc. AlN doped with TM atoms with a partially filled d orbital viz. Manganese, Chromium, Iron, Vanadium etc. belongs to this interesting class of semiconductors, that various studies has reported as good candidates for spintronic applications often owing to their half metallic properties.. Our earlier work involved the use of Anderson impurity model for DMSs to describe the tunnelling barrier of a model magnetic tunnel junction (MTJ) containing TM atoms and study the effect of gap states on the electronic transport. The Bloch energies are obtained using a DFT calculation as implemented in Vienna Ab initio simulation package (VASP) This approach provides a mean field rationale for the existence of free local moments on transition metal impurities that result from the interplay of orbital hybridization and the Coulomb interaction of the electrons at the impurity. We have investigated the electronic structure of the impurity and their magnetic moments for various values of the parameters that describe the SIAM to obtain the conditions for local moment formation Both (Al,Mn)N and (Al,Cr)N were observed to exhibit half metallic properties which could be exploited for spintronic applications. We envisage the use of this model in tuning the parameters continuously to drive such systems from a magnetic to non-magnetic state or vice-versa
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