Two-dimensional decoherence effects in superconducting sheets of single crystal Bi 2Sr 2CaCu 28+ x

Abstract

We quantitatively analyze ohmic magnetoresistance of a Ba 2Sr 2CaCu 2O 8+ x single crystal in the temperature range 40 K ⩽ T ⩽ 76 K and in magnetic fields up to 0.8 T, with an emphasis on the non-Arrhenius high-resistivity data. The unusual field dependence of the magnetoresistance at high resistivities is shown to follow a behaviour which is characteristic for decoherence effects in two-dimensional systems. We give semiquantitative arguments which relate the observed behaviour to the magnetic-field-induced breaking of non-dissipative quasiparticle pairs occurring in the mixed state within the isolated double CuO 2 sheets. These arguments generalize the approach to the quantum decoherence phenomena, originally developed for T > T c, to T < T c.