Energy Gap Structure in Bilayer Oxide Superconductors

Abstract

We consider a model for bilayer superconductors where an interlayer pairing amplitude ${\Delta }_{\perp }$ co-exists with intralayer pairing ${\Delta }_{\Vert }$ of $d_{x^2-y^2}$ symmetry. This model is motivated by a recent photoemission experiment reporting the splitting of the nodes of the energy gap. In addition to offering a natural explanation of this observation, the model has a number of new experimental consequences. We find that the new state is accompanied by a spontaneous breaking of the tetragonal symmetry. We also find that the out-of-phase oscillation of ${\Delta }_{\perp }$ and ${\Delta }_{\Vert }$ gives rise to a new Raman active mode. The phase of ${\Delta }_{\perp }$ may also become imaginary, leading to a state which breaks time reversal symmetry, which may have important implications for tunnelling experiments.

4 pages, Revtex, 1 figure. The discussion of the phase mode has been extended.

References in corpus (2)

• Spin Gaps and Spin Dynamics in La_{2-x}Sr_xCuO_4 and YBa_2Cu_3O7_δ
• Fractional Vortices as Evidence of Time-Reversal Symmetry Breaking in High-Temperature Superconductors

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• c-axis Josephson Tunnelling in Twinned and Untwinned YBCO-Pb Junctions
• Collapse of density wave and emergence of superconductivity in pressurized-La${}_4$Ni${}_3$O${}_{10}$ evidenced by ultrafast spectroscopy
• Collective modes in the electronic polarization of double-layer systems in the superconducting state
• Superconductivity in La${}_4$Ni${}_3$O${}_{10}$ Under Pressure
• Thermal Fluctuations in d-wave Layered Superconductors