Electronic, and Magnetic Properties of Tm Doped ZnO: A First Principle Study

The electronic, magnetic and optical properties of pure and thulium (Tm) doped ZnO have been investigated by using first principle method. We applied Generalized Gradient Approximation (GGA), GGA+U where U is Hubbard parameter and Tran-Blaha modified Becke-Johnson (TB-mBJ) for exchange correlation potential. The band gap value calculated by TB-mBJ is 2.79 eV, which is in good agreement with the experimental value. Then we doped ZnO with Tm using a super cell of 1x 1 x 2 (16 atoms) with 25% atomic concentration of Tm. It is found that the Tm doped ZnO system became anti-ferromagnetic (AFM) in ground state for Far configuration, whereas for Near configuration, the system of Tm-doped ZnO is ferromagnetic (FM) degenerate semiconductor. It is observed from density of states that there is spin polarization in states of Tm-doped ZnO so it has net magnetic moment. The formation energy is also increased with the decrease of the distance between the atoms of Tm.