Anisotropy in the electrical resistivity and upper critical magnetic field of single-crystal Pb 2Sr 2Ho 0.5Ca 0.5Cu 3O 8

Abstract

The anisotropy in the electrical resistivity ϱ and the anisotropy in the upper critical magnetic field H c2 have been investigated for Pb 2Sr 2Ho 0.5Ca 0.5Cu 3O 8 single crystals. The anisotropy in the resistivity, ϱ c ϱ ab, is 29 at 3 00K and 140 at 100K. The anisotropy in H c2 has been determined from the angular dependence of ϱ ab(H, θ) under various constant magnetic fields. The angular dependence of H c2 is well explained by the effective mass model. The value of γ ≡ H c2 |/H c2 ⊥ is estimated as 12, which is larger than the 4–5 in YBa 2Cu 3O 7 and much smaller than the 19–200 in Bi 2Sr 2CaCu 2O 8. Consequently, it has been concluded that the anisotropy does not always depend on the thickness of the blocking layer but on the overlap of the electronic wave functions along the c-axis.