Effective theory of Fermi pockets in fluctuating antiferromagnets

Abstract

We describe fluctuating two-dimensional metallic antiferromagnets by transforming to a rotating reference frame in which the electron spin polarization is measured by its projections along the local antiferromagnetic order. This leads to a gauge-theoretic description of an 'algebraic charge liquid' involving spinless fermions and a spin S = 1/2 complex scalar. We propose a phenomenological effective lattice Hamiltonian which describes the binding of these particles into gauge-neutral, electron-like excitations, and describe its implications for the electron spectral function across the entire Brillouin zone. We discuss connections of our results to photoemission experiments in the pseudogap regime of the cuprate superconductors.1 arXiv:0912.0943v2 [cond-mat.str-el]

Fermi surface reconstruction in hole-dopedt−Jmodels without long-range antiferromagnetic order

“…The quasiparticle residue was anisotropic around the Fermi surface, but our approximation did not yield the strong variation found in earlier phenomenological models. 18 We note a recent independent study 31 to describing the under-doped cuprates as a "Luttinger-volume violating Fermi liquid" (LvvFL) with a spin liquid of fermionic spinons. The LvvFL state is qualitatively the same as the FL* state.…”

“…This paper describes a FL* state in a single-band model appropriate for the cuprate superconductors. Previous studies 18,19 realized such a state by initially fractionalizing the electron into a neutral S = 1/2 spinon, and a spinless "holon" carrying electromagnetic charge. The spinons eventually became the excitations of a 'background' spin liquid, analogous the spin liquid of the f electrons above.…”

Fermi surfaces and gauge-gravity duality

“…The bosonic spin excitations have an energy gap 2 1 − 2 2 , as is easily seen by diagonalizing the quadratic form of L σ . The combined theory L d + L σ has a number of possible phases, distinct from the doublon metal [34,[44][45][46][47]. Condensation of b ±σ breaks the U(1) gauge symmetry and leads to antiferromagnetic order.…”

Quantum oscillations in the high- T c cuprates

“…Among possibilities suggested for an unconventional origin of magneto-oscillations are spinless fermions [45,46], charge 2e bosons [47], low-energy Andreev-type bound states [48], oscillations originating from the vortex lattice [49,50,51], or Fermi points accompanied by a shift in chemical potential [52]. These possibilities, however, need to be examined for their agreement with Fermi-Dirac statistics observed by quantum oscillations and measured 1/B periodicity over an extended field range (discussed in §2), as well as the doping dependence of the frequency and effective mass (discussed in §3).…”