Comparison of critical properties in MgB2 nanometer films prepared on SiC/Si substrate

11th European Conference on Applied Superconductivity

Nishida, A.^1 ; Taka, C.^1 ; Chromik, S.^2 ; Durny, R.^3

Department of Applied Physics, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku Fukuoka

814-0180, Japan^1

Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava

841 04, Slovakia^2

Department of Physics, Faculty of Natural Sciences, Constantine the Philosofer University, Tr. A. Hlinku 1, Nitra

949 01, Slovakia^3

关键词: Critical current density Jc;    Critical properties;    Diamagnetic susceptibility;    Irreversibility fields;    Parallel magnetic field;    Superconducting properties;    Temperature dependence;    Upper critical fields;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/507/1/012036/pdf
DOI  :  10.1088/1742-6596/507/1/012036

来源: IOP

【 摘 要 】

Critical superconducting properties in 100nm MgB2film are investigated and examined in comparison with our previous results in 10nm and 50nm films. MgB2films were prepared by sequential evaporation of boron and magnesium on SiC-buffered Si substrate followed by in situ annealing. The amount of supplied boron was controlled so as to result in the required MgB2film thickness with excess Mg top layer. The superconducting transition temperature Tcis estimated to be 33.1K from the onset of AC diamagnetic susceptibility. The upper critical field Hc2is also estimated from the AC susceptibility. Their temperature dependences are almost linear with |dHc2/dT|∼5.6kOe/K for the parallel magnetic field and |dHc2/dT]∼3.9kOe/K for the perpendicular field. These values are larger than those in our previous 50nm film (Tcof 34.5K) in spite of a little lower transition temperature. The critical current density Jc and irreversibility field Hirrare estimated from DC magnetization hysteresis. Scaling behavior of Hirr∼ [1-(T/Tc)2]nis examined in comparision to our previous studies in 10nm and 50nm films with different critical exponents n.