Quantum oscillations in high-temperature superconductors

The observation of quantum oscillations in underdoped cuprates
has generated intense debate about the nature of the field-induced
resistive state and its implications for the enigmatic `normal
state' of high-temperature superconductors. Quantum oscillations
suggest an underlying Fermi liquid at high magnetic fields H and low
temperatures, in contrast with the `pseudogap' seen in zero-field,
high-temperature spectroscopic experiments. Recent specific heat
measurements show quantum oscillations in addition to a large
field-dependent suppression of the electronic density of states. I
will present a theoretical analysis [1] that reconciles these
seemingly contradictory observations. I will give a general
introduction to `fermiology' of cuprate superconductors, namely
quantum oscillations, electronic spectra and Fermi surface
reconstruction. Then I will discuss our approach that models the
field-induced resistive state as a vortex liquid with short-range
d-wave pairing correlations. We show that this state exhibits
quantum oscillations, with a period determined by a Fermi surface
reconstructed by a possible translational symmetry-breaking order
parameter, in addition to a large suppression of the density of
states that goes like square root of H at low fields. 

1. S. Banerjee, S. Zhang and M. Randeria, Nature Comm. 4:1700 (2013).