S 93 Superconducting Properties of the Atomically Disordered MgB2 Compound / A. E. Kar'kin, V. I. Voronin, T. V. D'yachkova, N. I. Kadyrova, A. P. Tyutyunnik, V. G. Zubkov, Yu. G. Zainulin, M. V. Sadovskii, B. N. Goshchitskii // JETP Letters. - 2001. - Vol. 73, № 10. - P. 570-572 : il. - Bibliogr. : p. 572 (10 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): СВЕРХПРОВОДИМОСТЬ -- ДИБОРИД МАГНИЯ Аннотация: The effect of disorder induced by neutron irradiation in a nuclear reactor (thermal neutron fluence 1x 10(19) cm–2) on the superconducting transition temperature Tc and the upper critical field Hc2 of polycrystalline MgB2 samples was investigated. Despite the appreciable radiation-induced distortions (more than ten displacements per atom), the initial crystal structure (C32) was retained. The temperature Tc decreased from 38 to 5 K upon irradiation and was practically completely restored after the subsequent annealing at a temperature of 700°C. A weak change in the dHc2/dT derivative upon irradiation is explained by the fact that the irradiated samples are described by the “pure” limit of the theory of disordered superconductors. The suppression of Tc upon disordering may be due to the isotropization of the originally anisotropic (or multicomponent) superconducting gap or to a decrease in the density of electronic states at the Fermi level Полный текст |