Record upper critical field in C-doped bulk MgB2

04 November 2020 par Super Administrateur

Researchers from the University of Geneva took advantage of the LNCMI 35 T DC resistive magnet in order to set a new record upper critical field Hc2 in bulk MgB2 doped with carbon. MgB2 is currently used in practical applications for electrical power transport and magnetic field generation. For such applications, the upper critical field Hc2, that sets the limit for superconductivity, must be maximized. The full potential of MgB2 remains to be unleashed, as indicated by large upper critical fields measured in thin films. To unlock this potential, the team devised an experimental plan in order to explore the vast parameter space of bulk MgB2-xCx synthesis. The samples were characterized and their resistivities have been measured at the LNCMI in order to determine what synthesis conditions yield the highest Hc2. This work shows that Hc2 in bulk C-doped MgB2 is bounded to a maximum value of 35 T at 4.2 K.

Publication - High‑field superconductivity in C‑doped MgB2 bulk samples prepared by a rapid synthesis route - D. Matera, M. Bonura, R. Černý, S. McKeown Walker, F. Buta, D. LeBoeuf, X. Chaud, E. Giannini & C. Senatore, Scientific Reports 10 17656 (2020)

Figure Resistance of a C-doped MgB2 sample as a function of magnetic field measured at different temperatures. Upon increasing magnetic field, the superconducting state, indicated by zero resistance, is suppressed and the normal state resistance RN is restored above Hc2.

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