Enhancement of the spin-glass transition temperature through pd -orbital hybridization in Zn1−xMnxTe

Abstract

To gain insight into the spin-glass state of diluted magnetic semiconductors, we have examined the magnetic and electronic properties of Zn1−xMnxTe using density functional theory as well as performed magnetization measurements on the x = 0.43 and 0.55 systems to demonstrate a clear spin-glass transition consistent with previous literature. Using a generalized gradient approximation, we investigate the electronic and magnetic properties for x = 0, 0.25, and 0.50 doping levels using the magnetic moment of Mn 2+ as guide for the dependence of the Hubbard onsite potential on the electronic structure. Simulations on both ferromagnetic (FM) and antiferromagnetic (AFM) configurations yield a distinct AFM ground state preference, which is consistent with a zero magnetic moment spin glass state. Here, an onsite potential of up to 8 eV on the Mn 3d-orbitals is needed to harden the magnetic moment toward S = 5/2. From our analysis of the electronic structure evolution with doping and onsite potential, we confirm the semiconducting state of the Mn-doped ZnTe as well as show that the presence of Mn incorporated into the ZnTe matrix at the Zn lattice site produces magnetic interactions through the Te ions with a distinct Te-Mn pd-orbital hybridization. Furthermore, we show that this hybridization is activated with the Mn doping above 0.25 concentration, which corresponds to the doping level in which the spin-glass transition begins to rise. Therefore, it is likely that the coupling of pd-orbital hybridization of the Mn and Te p-orbitals is a precursor to the enhancement of the spin-glass transition temperature.