PREPARATION AND PHOTOLUMINESCENCE PROPERTIES OF RF-SPUTTERED ZnO FILMS

ZnO/Si films were prepared by radio frequency (RF) magnetron sputtering at room temperature. By optimizing the heat treatment conditions, we obtained a good quality film annealed at 700 ºC for longer 60 minutes. This process was monitored carefully by Raman scattering spectroscopy, and X-ray diffraction. The photoluminescence study on this film revealed that only ultraviolet emissions due to donor-acceptor pair (DAP), neutral acceptor-bound exciton (AºX) and donor-bound exciton (DºX) were observed. The intensity and peak position of these emissions depend on the measurement temperature and excitation power density

The Structure And Magnetic Properties Of Fe0.50cr0.50-Xsix (X=0-0.1) Nano Materials Prepared Via Mechanical Alloying Technique

The main objective of this study is the investigation of the relationship between the structure and the magnetic properties of Fe50Cr50-xSix (x=0-0.1) metastable alloys which were made by mechanical alloying for 36 hours. Research in this field feels still lacking. To understand the structure using by X-ray diffraction (XRD) and the magnetic properties are measured by using a Physical Property Measurement System (PPMS). The result with variable of x = 0-, 0.025-, 0.050-, 0.075- and 0.1 wt. %. are crystallite sizes (D) increase from 7 to 8.5 nm, the structural strains (ϵ) are down about 20% from normal circumstances. The grain sizes increase causing the number of domains to increase then the mobility of domain decreases or coercivity (Hc) decreases from 120 to 40 Oe. In amorphous state coercivity rises and crystallite sizes decrease, suddenly

Second order magnetic phase transition and scaling analysis in iron doped manganite La0.7Ca0.3Mn1−xFexO3 compounds

We investigated magnetic properties of La0.7Ca0.3Mn1-xFexO3 (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La0.7Ca0.3Mn1-xFexO3 (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x \u3c 0.09) in previous reports.When we investigate the critical behavior of thecompounds near T=Tc by the modified Arrott plot, Kouvel-Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε-βM(H,ε) and renormalized field h=|ε|β+γH. Temperature-dependent effective exponents βeff and γeff correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration

Second order magnetic phase transition and scaling analysis in iron doped manganite La0.7Ca0.3Mn1−xFexO3 compounds

We investigated magnetic properties of La0.7Ca0.3Mn1-xFexO3 (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La0.7Ca0.3Mn1-xFexO3 (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x \u3c 0.09) in previous reports.When we investigate the critical behavior of thecompounds near T=Tc by the modified Arrott plot, Kouvel-Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε-βM(H,ε) and renormalized field h=|ε|β+γH. Temperature-dependent effective exponents βeff and γeff correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration