engleski

Two-dimensional decoherence effects in superconducting sheets of single crystal Bi_2Sr_2CaCu_2O_8+x

We quantitatively analyze ohmic magnetoresistance of a Bi2Sr2CaCu2O8+x Single crystal in the temperature range 40 K less than or equal to T less than or equal to 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 CuO2 sheets. These arguments generalize the approach to the quantum decoherence phenomena, originally developed for T >T-c to T <T-c.

magnetoresistance; fluctuation effects; pair breaking

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