Specific heat of MgB_2 after irradiation

Abstract

We studied the effect of disorder on the superconducting properties of polycrystalline MgB_2 by specific-heat measurements. In the pristine state, these measurements give a bulk confirmation of the presence of two superconducting gaps with 2 Delta 0 / k_B T_c = 1.3 and 3.9 with nearly equal weights. The scattering introduced by irradiation suppresses T_c and tends to average the two gaps although less than predicted by theory. We also found that by a suitable irradiation process by fast neutrons, a substantial bulk increase of dH_{c2}/dT at T_c can be obtained without sacrificing more than a few degrees in T_c. The upper critical field of the sample after irradiation exceeds 28 T at T goes to 0 K.

11 pages text, 6 figures, accepted by Journal of Physics: Condensed Matter

References in corpus (2)

• Vortex Imaging in the pi-Band of Magnesium Diboride
• Specific heat of single crystal MgB_2: a two-band superconductor with two different anisotropies

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