Flux pinning properties of MgB2 thin films on Ti buffered substrate prepared by molecular beam epitaxy

Abstract

Transport properties of the MgB 2 thin films on Si, MgO and ZnO substrates with Ti buffer layer prepared by molecular beam epitaxy were investigated to clarify effects of the substrates and the Ti buffer layer on flux pinning. The critical current density J c of each sample shows different dependence on magnetic fields parallel to c-axis. However, the scaling analysis of the macroscopic pinning force for all the measured samples implies that the grain boundaries work as the dominant pinning centers for B//c. The pinning parameter for MgB 2 /Ti/Si estimated from the electric field E vs. the current density J characteristics shows the highest value among all the measured samples. This result is attributed to the high density of grain boundaries caused by the effect of both the Ti buffer and Si substrate in the growth process. Therefore, the selection of substrates and buffer layer strongly affects the flux pining properties of MgB 2 thin films and plays an important role in the determination of performance for superconducting devices and wires.

Microstructure of MgB 2 superconducting wire prepared by internal magnesium diffusion and in-situ powder-in-tube processes – Secondary phase intergrain nanolayers as an oxygen content indicator

“…Thus we can conclude that the MgO plates are oriented with (0 0 1) MgO planes parallel to (0 0 1) MgB2 MgB 2 planes. This mutual orientation of cubic MgO and hexagonal MgB 2 phases has already been observed and discussed [25][26][27][28][29][30][31]. 1 0 MgO [29].…”

“…The film was polycrystalline and it did not have any preferential in-plane orientation, only strong [0 0 1] MgB2 out-of-plane texture. Some other authors also published c-oriented MgB 2 thin film on (0 0 1) MgO substrate without any additional information about the in-plane orientation[26][27][28]. Tian et al showed clear epitaxial growth of (…”