High-field interlayer tunnelling transport in layered cuprates: Uncovering the pseudogap state

摘要

In high temperature (high T-c) cuprate superconductors the gap in the electronic density of states is not fully filled at T-c ; it evolves into a partial (pseudo)gap that survives way beyond T-c , challenging the conventional views. We have investigated the pseudogap phenomenon in the field-temperature (H-T) diagram of Bi2Sr2CaCu2O8+y over a wide range of hole doping (0.10less than or equal topless than or equal to0.225). Using interlayer tunneling transport in magnetic fields up to 60 T to probe the density-of states (DOS) depletion at low excitation energies we mapped the pseudogap closing field H-pg . We found that H-pg and the pseudogap onset temperature T*supercript stop are related via a Zeeman relation gmu(B)H(pg)approximate tok(B)T*, irrespective of whether the magnetic field is applied along the c-axis or parallel to CuO2 planes. In contrast to large anisotropy of the superconducting state, the field anisotropy of H-pg is due solely to the g-factor. Our findings indicate that the pseudogap is of singlet-spin origin, consistent with models based on doped Mott insulator.