Alladi Ramakrishnan Hall

Quantum oscillations in high-temperature superconductors

Sumilan Banerjee

Ohio State University

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 fieldinduced 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.