Study Of Effect On Magneto-Optical Properties Of Mn Or Cr Double-Doped ZnO

Although good results on the effects of Mn and Cr doped ZnO have been theoretically and experimentally achieved,there are still shortcomings in the researches.In order to explore the reasons for the controversies,the structural stability,electronic structures,absorption spectra and magnetic properties of Mn and Cr doped ZnO with and without oxygen vacancy along c axis and perpendicular to c axis were calculated using the method of generalized gradient approximation(GGA+U)based on the first-principles plane-wave pseudopotential of the spin-polarized density functional theory(DFT).For the doped systems without oxygen vacancy,with the magnetic particle distance gradually increases,the structure of the systems Mn or Cr double doped and(Mn,Cr)co-doped along the c-axis direction became more stable.For the systems Mn or Cr double doped along the direction of perpendicular to c-axis,the structure became more stable with the magnetic particle distance gradually increase,but the stability of(Mn,Cr)co-doped systems became lower.For the doped systems with oxygen vacancy,the trend of stability of doped systems along the c-axis direction is the same with systems without oxygen vacancy;the stability of the systems Mn double-doped along the direction of perpendicular to c-axis became lower with the distance of magnetic particles,the stability of Cr double-doped and Mn-Cr doped systems enhanced.For the doped systems along the direction of perpendicular to c-axis,the Curie temperature of Mn or Cr double-doped system with oxygen vacancy can reach above room temperature,but(Mn,Cr)co-doped system with oxygen vacancy was not above room temperature.Moreover,only the Curie temperature of the(Mn,Cr)co-doped system without oxygen vacancy can reach room temperature.In the wavelength range from 250 nm to 350 nm,for the doped systems without oxygen vacancy,the systems Mn or Cr double doped and(Mn,Cr)co-doped along c-axis direction showed a blue-shift in their absorption spectra.With the distance of the magnetic particle increase;in the perpendicular to c-axis direction,a blue-shift was observed in the absorption spectra of the Mn-doped system,the absorption spectrum weakened with the distance of the doping atoms increase;Cr double-doped and(Mn,Cr)co-doped system absorption spectrum showed a blue-shift,and the blue-shift enhanced with the distance of the doping increase.For the doped systems with oxygen vacancy,the absorption spectra of systems Mn double doped and(Mn,Cr)co-doped along c axis systems showed a red-shift.The red-shift was weakened with the distance of the doping increase;for the absorption spectrum of Cr double-doped system,the red-shift of absorption spectrum increases with the distance of doping increase.A red-shift was also observed in the systems Mn or Cr double-doped and(Mn,Cr)co-doped system along the perpendicular to c-axis direction,but the red-shift enhanced with the distance of doping increase.Based on first-principle,with oxygen vacancy or without oxygen vacancy,the absorption spectrum and magnetic for Mn or Cr double doped ZnO along c axis and perpendicular to c axis were calculated,and the divergence in experiment and theory were solved.It may be helpful to the design and preparation of the new optical and Magnetic function materials using ZnO.