QED3 Theory of High Temperature Superconductors • What is the ...

HTS are unique not only because they have such high T c and strong
vortex-antivortex fluctuations. They are also d-wave superconductors,
in contrast to conventional s-wave superconductors. ⇒
Low energy effective theory must contain FERMIONS !! This is in
contrast to He-type (BOSON ONLY) models of SC fluctuations
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s-wave superconductors: The gap function
∆(k) does not change sign on the Fermi
surface. The quasiparticle spectrum is
gapped: E(k) = ± √ (ε(k) − µ) 2 + |∆| 2
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d-wave superconductors: The gap function
∆(k) changes sign on the Fermi
surface. The quasiparticle spectrum is
gapless near the nodes, where ∆(k) → 0
E(k) = ± √ (ε(k) − µ) 2 + |∆(k)| 2 ∼ ±|k|
⇒ Massless Dirac Fermions !! ⇐