Absolute Value and Anisotropy of the Magnetic Penetration Depth in YBa2Cu3O6.92

The absolute value and anisotropy of the magnetic penetration depth have been measured in a mosaic of optimally-doped YBa2Cu3O6.92 crystals using low-energy muon spin rotation at 8 K with extrapolation to T = 0 using microwave resonator data. The average magnetic field was measured as a function of muon implantation energy in a small magnetic field applied along the â and directions. Beyond a depth d, the magnetic field profiles are consistent with the simple exponential decay of the internal field expected from a London model. The results are compared with other less direct methods.