MgB2 결정립 나노브릿지 특성에 관한 연구

Abstract

Inter-grain nanobridges of the MgB2 superconductor have been fabricated by focused-ion-beam (FIB) and their electrical transport properties were studied. The MgB2 film was prepatterned into microbridges by a standard argon ion milling technique and then FIB-patterned into 100 nm x 100 nm bridges. Current-voltage characteristics showed a strong flux-flow type behavior at all temperatures with a trait of Josephson coupling near Tc. At low temperatures, the curves showed a two-step resistance-doubled transition with occasional hysteresis. The resistance-doubling transition is believed to be due to a two-channel flux-flow effect. The temperature-dependent critical current data showed Ic(T) ∝ (1-T/Tc)2 near Tc, same as a normal barrier junction, and Ic(T) ∝ (1-T/Tc)1.2 at low temperatures, similar to that of a film.