Photoinduced Nanodots in Bi2Sr2CaCu2O8+d
We report a fabrication of high-density nanodots by photodoping in overdoped Bi2Sr2CaCu2O8+d thin film (Tc = 80 K). A scanning near-field optical microscope probe is used to locally excite carrier, and photodoped region is associated with lower Tc phase (Tc = 75 K) via overdoping. Nanoscale characterizations with optical reflectivity reveal that nanodots (30-nm diameter) are regularly distributed in 50-nm step. The resultant films with photoinduced nanodots enhance Jc, a situation being similar to strong pinning effects observed in films modified by either ion irradiation or sputtered nanoparticles. These results suggest that photoinduced nanodots with lower Tc act as effective pinning centers.
Keiichi Katayama, Kazumi Kato, Tadashi Takenaka, Masasuke Takata and Kazuo Shinozaki
M. Osada, M. Kakihana, H. Yasuoka, M. Käll, L. Börjesson, "Photoinduced Nanodots in Bi2Sr2CaCu2O8+d", Key Engineering Materials, Vol. 320, pp. 167-170, 2006