Projected SO(5) Hamiltonian for Cuprates and Its Applications
arXiv:cond-mat/0009421 · doi:10.1142/S0217979201006331
Abstract
The projected SO(5) (pSO(5)) Hamiltonian incorporates the quantum spin and superconducting fluctuations of underdoped cuprates in terms of four bosons moving on a coarse grained lattice. A simple mean field approximation can explain some key feautures of the experimental phase diagram: (i) The Mott transition between antiferromagnet and superconductor, (ii) The increase of T_c and superfluid stiffness with hole concentration x and (iii) The increase of antiferromagnetic resonance energy as sqrt{x-x_c} in the superconducting phase. We apply this theory to explain the ``two gaps'' problem found in underdoped cuprate Superconductor-Normal- Superconductor junctions. In particular we explain the sharp subgap Andreev peaks of the differential resistance, as signatures of the antiferromagnetic resonance (the magnon mass gap). A critical test of this theory is proposed. The tunneling charge, as measured by shot noise, should change by increments of Delta Q= 2e at the Andreev peaks, rather than by Delta Q=e as in conventional superconductors.
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References in corpus (5)
- First-principles and semi-empirical calculations for bound hole polarons in KNbO3
- Shot noise and coherent multiple charge transfer in superconducting quantum point-contacts
- Projected SO(5) Models
- Tunneling Spectra and Superconducting Gap in Bi2Sr2CaCu2O8+d and Tl2Ba2CuO6+d
- Superconductivity and Quantum Spin Disorder in Cuprates