Tl2Ba2CaCu2O8 bicrystal Josephson junctions operated close to 100 K

We have fabricated Tl2Ba2CaCu2O8 (Tl-2212) bicrystal Josephson junctions (BJJs) on LaAlO3 substrates and operated them at bath temperatures close to 100 K. The current-voltage characteristics of BJJs reveal that the critical current I-c has a power-law relationship with temperature. In addition, the normal resistance R-n has a universal value independent of the bath temperature. The performance of BJJs exhibits a perfect agreement with the Ambegaokar-Halperin model close to 100 K. Under microwave irradiation, Shapiro steps were clearly observed, confirming the genuine Josephson coupling through the grain boundary. We demonstrate that the maximum operating temperature of the proposed junction is up to 100 K, which is fairly close to the T-c of the specimen. The results of Tl-2212 bicrystal Josephson junctions may open a new perspective in further studies on low-cost and portable superconducting devices.