Abstract:
This paper reports on the results of investigations of the influence of irradiation of the two-band BCS superconductor MgB$_2$ by electrons with an average energy $\bar E\sim$ 10 MeV at high doses (0 $\le\Phi t\le\sim$ 2.5 $\times$ 10$^{18}$ cm$^{-2}$) on the temperature and width of the transition to the superconducting state, the temperature dependence of the electrical resistivity in the normal state, the crystal lattice parameters, and the diffraction line intensity. An increase in the electron irradiation dose $\Phi t$ leads to the following effects: a decrease in the critical temperature $T_c$; an increase in the width of the superconducting transition $\Delta T_c$; and a decrease in the “residual electrical resistivity” $\rho_{273 K}/\rho_{40 K}$, in the parameters $a$ and $c$ of the hexagonal crystal lattice, and in the ratio between the diffraction line intensities $I_{110}/I_{100}$. From analyzing the results obtained, it has been established that the main type of radiation damages under irradiation of the BCS superconductor MgB$_2$ by high-energy electrons is the formation of vacancies in the B sublattice, which leads to a narrowing of the large band gap $\Delta\sigma$ on the Fermi surface.
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