Investigation of the insulator to half-metal transition in Cr-doped ZnO at low temperature (19 K)‎ wurtzite structure

Abstract EN

The structural, electronic and magnetic properties of pure and Cr-doped ZnO with a low temperature (19 K) wurtzite structure were studied by employing density functional theory (DFT) as implemented in the tight-binding linearized muffin-tin orbital (TB-LMTO) method.

Pure ZnO is observed as a nonmagnetic insulator in which all the Zn-3d orbitals are found occupied and electrons are perfectly paired in each orbital causing nonmagnetic nature of pure ZnO.

But Cr-doping in ZnO significantly changes its electronic and magnetic properties.

This material encounters nonmagnetic insulator to a ferromagnetic half-metal with minute structural distortions at 50% Cr substitution for Zn.

This study revealed that the doped material Zn Cr 50 is metallic for the majority spin species and insulating for the minority spin species with a semiconducting gap of 3.5 eV.

Due to the influence of the strong electron correlation effect, three Cr-t, orbitals become fully occupied by three Cr-3d electrons, while remaining single electron is shared by two e orbitals in the close vicinity of the Fermi level.

This sharing of the single electron by two e orbitals is responsible for the metallic behavior of Zn, CrO for the spin majority channel.

The parallel alignment of unpaired electrons in the Cr-3d orbitals is responsible for the ferromagnetism of this material.