Doctor of Philosophy (Ph.D.)
William J Kossler
Transverse Field muon spin relaxation (TF-muSR) experiments were performed in external magnetic fields 1.0, 2.7, 3.0, 4.5, 5.5, 6.0 and 7.0 T along the Bi2212 crystalline c-axis. For the first time, the heterodyned fitting analysis technique shows that the field profiles on the ab basal planes of single crystal Bi2212 are symmetric in all experimental fields 1.0--7.0 T and at all experimental temperatures 2.0-90.0 K. The muon spin relaxation rates due to the mixed state of Bi2212 were found to increase linearly from 0 mus-1 at the transition temperature, 90.0 K, to about 1.0 mus -1 at the lowest temperature, 2.0 K. The relaxation rates have much less field dependence than the temperature dependence and the field dependence of the relaxation rate is of opposite sign to that seen for YBCO, which is undoubtedly due to vortex lattice disorder caused by the weak coupling between the CuO planes. The scaled magnetic field penetration depths ll0 were found to be independent of magnetic field B in the temperature range 0--50.0 K. Fitting ll0 by currently available models was attempted. A proposed pancake vortex disorder model strongly suggests pancake disordering at all temperatures including 2.0 K, the lowest temperature reached in our experiment. Our experiments and the computer simulation from the pancake vortex disorder model showed that muSR data in this temperature and field range are attributed to the 2-D anisotropic vortex characteristics of Bi2212.
© The Author
Wan, Xuewen, "Effects of longitudinal disorder on the magnetic field distribution in bismuth strontium calcium copper oxide" (2002). Dissertations, Theses, and Masters Projects. Paper 1539623413.