Correlation between defect and magnetism of low energy Ar+9 implanted and un-implanted Zn0.95Mn0.05O thin films suitable for electronic application

• Synthesis of transparent 5 at% Mn doped ZnO films was done by sol-gel technique.
• Defect induced intrinsic ferromagnetism was observed for Ar9+ ion implanted films.
• The maximum magnetization was attained for highest dose of Ar9+ implantation.
• Zn vacancy may favors intrinsic ferromagnetic ordering.
• Intrinsic ferromagnetism was interpreted in terms of bound magnetic polaron model.

The structural, morphological, optical and magnetic properties of Ar+9 implanted 5 at% Mn doped ZnO films have been investigated to detect the correlation between ferromagnetism (FM) and defect. Sol–gel derived films were implanted with fluences 0 (un-implanted), 5×1014 (low), 1015 (intermediate) and 1016 (high) ions/cm2. Rutherford back scattering (RBS), X-ray diffraction (XRD), atomic force microscope (AFM) and magnetic force microscope (MFM), UV–visible, photoluminescence and X-ray absorption spectroscopy (XAS) and superconducting quantum interference device vibrating sample magnetometer (SQUID VSM) were employed for investigation. XRD indicated single phase nature of the films. Absence of impurity phase has been confirmed from several other measurements also. Ion implantation induces a large concentration of point defects into the films as identified from optical study. All films exhibit intrinsic FM at room temperature (RT). The magnetization attains the maximum for the film implanted with fluence 1016 ions/cm2 with saturation magnetization (MS) value 0.69 emu/gm at RT. Magnetic properties of the films were interpreted using bound magnetic polaron (BMP). BMP generated from the intrinsic exchange interaction of Mn2+ ions and VZn related defects actually controls the FM. The practical utility of these films in transparent spin electronic device has also been exhibited.

Figure optionsDownload as PowerPoint slide