Search for: All records

We describe the confining instabilities of a proposed quantum spin liquid underlying the pseudogap metal state of the hole-doped cuprates. The spin liquid can be described by a SU(2) gauge theory ofN_f= 2 massless Dirac fermions carrying fundamental gauge charges—this is the low-energy theory of a mean-field state of fermionic spinons moving on the square lattice withπ-flux per plaquette in the ℤ₂center of SU(2). This theory has an emergent SO(5)_fglobal symmetry and is presumed to confine at low energies to the Néel state. At nonzero doping (or smaller Hubbard repulsionUat half-filling), we argue that confinement occurs via the Higgs condensation of bosonic chargons carrying fundamental SU(2) gauge charges also moving inπℤ₂-flux. At half-filling, the low-energy theory of the Higgs sector hasN_b= 2 relativistic bosons with a possible emergent SO(5)_bglobal symmetry describing rotations between ad-wave superconductor, period-2 charge stripes, and the time-reversal breaking “d-density wave” state. We propose a conformal SU(2) gauge theory withN_f= 2 fundamental fermions,N_b= 2 fundamental bosons, and a SO(5)_f×SO(5)_bglobal symmetry, which describes a deconfined quantum critical point between a confining state which breaks SO(5)_fand a confining state which breaks SO(5)_b. The pattern of symmetry breaking within both SO(5)s is determined by terms likely irrelevant at the critical point, which can be chosen to obtain a transition between Néel order andd-wave superconductivity. A similar theory applies at nonzero doping and largeU, with longer-range couplings of the chargons leading to charge order with longer periods.