Pseudogap in YBa_2Cu_3O_6+δ is not bounded by a line of phase transitions: Thermodynamic evidence

Cooper, J. R. and Loram, J. W. and Kokanović, Ivan and Storey, J. G. and Tallon, J. L. (2014) Pseudogap in YBa_2Cu_3O_6+δ is not bounded by a line of phase transitions: Thermodynamic evidence. Physical Review B, 89 (20). 201104(R)-5. ISSN 1098-0121

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Abstract

We discuss a recent resonant ultrasound spectroscopy (RUS) study of YBa_2Cu_3O_6+δ, which infers a line of phase transitions bounding the pseudogap phase and argue that this scenario is not supported by thermodynamic evidence. We show that the anomalies in RUS, heat capacity, and thermal expansion at the superconducting transition temperatures agree well, but there are large discrepancies between RUS and thermodynamic measurements at T∗ where the pseudogap phase transitions are purported to occur. Moreover, the frequency and temperature dependence of the RUS data for the crystal with δ=0.98, interpreted in terms of critical slowing down near an electronic phase transition, is five orders of magnitude smaller than what is expected. For this crystal the RUS data near T∗ are more consistent with nonequilibrium effects, such as oxygen relaxation.

Item Type: Article
Date: May 2014
Subjects: NATURAL SCIENCES > Physics
Additional Information: Copyright (2014) by the American Physical Society.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 26 Aug 2014 12:13
Last Modified: 26 Aug 2014 12:28
URI: http://digre.pmf.unizg.hr/id/eprint/2381

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