Speaker
Description
A conventional superconductor $MgB_{2}$ is considered as a candidate for various applications due to its high critical temperature ($T_c$~39 K) and current density ($J_c$) [1]. Ion irradiation on $MgB_{2}$ thin films induces disorder caused by the atomic lattice displacement, which leads to the reduction of $T_c$ [2,3]. In this study, we investigated the influence of He ion irradiation on the $MgB_{2}$ thin films of thicknesses of 170 nm and 570 nm with various does of irradiations. Changing of lattice constant and superconducting transition temperature of irradiated $MgB_{2}$ thin films were observed by x-ray diffraction (XRD) and electrical resistivity measurements, respectively. $T_c$ systematically decreases with increasing irradiation dose, however $T_c$ is still present near 8 K at maximum does ($4.8\times10^{16}atoms/cm^2$), meaning that superconductivity of $MgB_{2}$ thin film is robust against disorder produced by He ion irradiation. Furthermore, we will discuss the recovery of $T_c$ through thermal annealing on the irradiated $MgB_{2}$ thin films.
[1] Nagamatsu, J., Nakagawa, N., Muranaka, T. et al., “Superconductivity at 39 K in magnesium diboride” Nature 410, 63–64 (2001)
[2] Soon-Gil Jung et al., ”Influence of carbon-ion irradiation on the superconducting critical properties of MgB2 thin films” Supercond. Sci. Technol. 32 (2019) 025006
[3] Jung Min Lee et al., “Influence of disorder strength on the superconducting mechanism of MgB2” Supercond. Sci. Technol. 35 (2022) 015001
