Effect of Magnetic Field Direction on Magnetoresistivity, Activation Energy, Irreversibility and Upper Critical Field of Bi-2212 Thin Film Fabricated by DC Sputtering Method

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This study aims to investigate the effect of magnetic field direction on superconducting properties of Bi-2212 thin film fabricated on MgO (100) substrate using the direct current (DC) magnetron reactive sputtering technique at 100 watt with the aid of magnetoresistivity measurements. The zero resistivity transition temperatures (Tc), irreversibility fields (μ0Hirr) and upper critical fields (μ0Hc2) are deduced from the magnetoresistivity versus temperature curves under DC magnetic fields (parallel and perpendicular to c-axis) up to 5 T. Moreover, thermally activated flux flow (TAFF) model is studied for activation energy (U0) values of the sample. It is found that the Tc value decreases from 76.4 K to 39.1 K for the applied magnetic field perpendicular to c-axis (μ0H⊥c-axis); likewise, the Tc reduces towards 28.8 K with the increase in the applied field parallel to c-axis (μ0H∥c-axis). Furthermore, the U0 values are found to decrease considerably with increasing applied magnetic field. In fact, the U0 of 134.5 K is obtained to be smallest at 5 T field parallel to the c-axis. Additionally, both the μ0Hirr and μ0Hc2 values determined are also observed to reduce with the increase of the applied magnetic field. At absolute zero temperature (T=0 K), the extrapolation of the μ0Hirr(T) and μ0Hc2(T) curves is used to obtain the μ0Hirr(0) and μ0Hc2(0) values of the film, respectively. The inner is found to be about 22.216 T (19.046 T) for the applied field perpendicular (parallel) to c-axis whereas the latter is determined to be about 54.095 T (126.522 T) for the applied field parallel (perpendicular) to c-axis, respectively, as a result of anisotropic behavior of the film prepared. On the other hand, penetration depths (λ) and coherence lengths (ξ) inferred from μ0Hirr(0) and μ0Hc2(0) values are obtained to be about 38.519 A (41.601 A) and 16.147 A (24.685 A) in the case of applied field perpendicular (parallel) to c-axis, respectively. Based on all the results, the change of the superconducting properties as a function of the magnetic field direction presents the anisotropy of the sample produced. X-ray diffraction (XRD) and scanning electron microscopy (SEM) examinations are also conducted for microstructural and phase analyses of the film.