Volume 87, Number 1, July 2009
Article Number 17011
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 24 July 2009
EPL, 87 (2009) 17011
DOI: 10.1209/0295-5075/87/17011

Thermodynamic signature of a phase transition in the pseudogap phase of YBa2Cu3Ox high-TC superconductor

B. Leridon1, P. Monod1, D. Colson2 and A. Forget2

1   Laboratoire Photons Et Matière, UPR5/CNRS, ESPCI - 10 rue Vauquelin, 75231 Paris cedex 05, France, EU
2   Service de Physique de l'Etat Condensé, DSM/IRAMIS, CEA Saclay - 91191 Gif-sur-Yvette Cedex, France, EU

received 6 March 2009; accepted in final form 24 June 2009; published July 2009
published online 24 July 2009

We present here high-precision magnetisation measurements in polycrystalline YBa2Cu3Ox samples, with oxygen content ranging from x = 6.19 to x = 7.00. By analysing the temperature derivative of the susceptibility, we found in the underdoped superconducting samples a singular point at a temperature corresponding to Tmag, the temperature below which polarised neutrons experiments have evidenced a symmetry breaking. We believe that this is a thermodynamic indication for the existence of a phase transition in the pseudogap state of underdoped YBa2Cu3Ox.

74.25.Dw - Superconductivity phase diagrams.
74.72.Bk - Y-based cuprates.
74.25.Ha - Magnetic properties.

© EPLA 2009