The de Haas-van Alphen effect was observed in the underdoped cuprate YBa2Cu3O6.5 via a torque technique in pulsed magnetic fields up to 59 T. Above an irreversibility field of ∼30 T, the magnetization exhibits clear quantum oscillations with a single frequency of 540 T and a cyclotron mass of 1.76 times the free electron mass, in excellent agreement with previously observed Shubnikov-de Haas oscillations. The oscillations obey the standard Lifshitz-Kosevich formula of Fermi-liquid theory. This thermodynamic observation of quantum oscillations confirms the existence of a well-defined, close and coherent, Fermi surface in the pseudogap phase of cuprates.
@article{arxiv.0711.3559,
title = {de Haas-van Alphen oscillations in the underdoped cuprate YBa$_2$Cu$_3$O$_{6.5}$},
author = {C. Jaudet and D. Vignolles and A. Audouard and J. Levallois and D. LeBoeuf and N. Doiron-Leyraud and B. Vignolle and M. Nardone and A. Zitouni and R. Liang and D. A. Bonn and W. N. Hardy and L. Taillefer and C. Proust},
journal= {arXiv preprint arXiv:0711.3559},
year = {2009}
}