Upper Critical Fields up to 60T in Dirty Magnesium Diboride Thin Films

C. Ferdeghini; V. Ferrando; C. Tarantini; E. Bellingeri; G. Grasso; A. Malagoli; D. Marre'; M. Putti; P. Manfrinetti; A. Pogrebnyakov; J. M. Redwing; X. X. Xi; R. Felici; E. Haanappel

doi:10.1109/tasc.2005.848827

arXiv · cond-mat/0411404

Upper Critical Fields up to 60T in Dirty Magnesium Diboride Thin Films

C. Ferdeghini·V. Ferrando·C. Tarantini·E. Bellingeri·G. Grasso·A. Malagoli·D. Marre'·M. Putti·P. Manfrinetti·A. Pogrebnyakov·J. M. Redwing·X. X. Xi·R. Felici·E. Haanappel

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Abstract

Upper critical fields of several magnesium diboride thin films were measured up to 28 T at the Grenoble High Magnetic Field Laboratory (GHMFL) in Grenoble and up to 60 T at the Laboratoire National des Champs Magnetiques Pulses (LNCMP) in Toulouse. The samples were prepared both by pulsed laser deposition (PLD) and hybrid physical chemical vapour deposition (HPCVD) technique; they have critical temperatures between 29 and 39 K and normal state resistivities between 5 and 250 μohmcm; one of them has been intentionally doped with carbon. The measured critical fields were exceptionally high; we obtained the record value of 52 T at 4.2 K in the parallel orientation. In contrast with the BCS predictions, no saturation in Hc2 at low temperature was observed. Furthermore, films with a wide range of resistivity values showed similar critical fields, suggesting that in a two band system resistivity and Hc2 are not trivially linked. The high Hc2 values seem to be related with the expanded c-axis. The structure of one of the samples was carefully investigated with X-ray diffraction at European Synchrotron Radiation Facility (ESRF) in Grenoble.

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C. Ferdeghini, V. Ferrando, C. Tarantini, E. Bellingeri, G. Grasso, A. Malagoli, D. Marre', M. Putti, P. Manfrinetti, A. Pogrebnyakov, J. M. Redwing, X. X. Xi, R. Felici, E. Haanappel. 2004-11-16. Upper Critical Fields up to 60T in Dirty Magnesium Diboride Thin Films. https://doi.org/10.1109/tasc.2005.848827

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