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

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• Observation of the Crossover from Two-Gap to Single-Gap Superconductivity through Specific Heat Measurements in Neutron Irradiated MgB2
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• Thermodynamics of Two - Band Superconductors: The Case of MgB${}_2$
• The two colors of MgB2
• Superconducting and Normal State Properties of Neutron Irradiated MgB2
• Influence of the upper critical field anisotropy on the transport properties of polycrystalline MgB${}_2$
• Multi-band Superconductivity in the Chevrel Phases SnMo6S8 and PbMo6S8
• Intraband versus interband scattering rate effects in neutron irradiated MgB2
• Superconducting properties of nanocrystalline MgB${}_2$
• Role of interband scattering in neutron irradiated MgB${}_2$ thin films by Scanning Tunneling Spectroscopy measurements
• On the rate of Tc suppression by the interband impurity scattering in MgB2
• Local Tunneling Study of Three-Dimensional Order Parameter in the $\pi$-band of Al-doped MgB${}_2$ Single Crystals
• Theory of vortices in hybridized ballistic/diffusive-band superconductors
• Effects of Neutron Irradiation on Carbon Doped MgB2 Wire Segments
• Effect of disorder on the NMR relaxation rate in two-band superconductors
• Nonmagnetic impurity effects in MgB${}_2$
• Effect of disorder on the far-infrared conductivity and on the microwave conductivity of two-band superconductors
• Enhancing long-range order in disordered two-band s-wave superconductors