Charge order and the pseudogap in the underdoped cuprates: a quantum oscillation study

I will present quantum oscillation results on the underdoped copper-oxide superconductors to address the question of the interplay of the charge ordered ground state with the pseudogap. Specifically we experimentally distinguish between the two cases where charge order reconstructs a large paramagnetic Fermi surface predicted by band structure, or where charge order reconstructs a truncated Fermi surface where the density of states is restricted to the nodal region, as observed in the pseudogap state.