Unconventional isotope effects in cuprate superconductors

Hugo Keller 

Physik-Institut der Universität Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland

Abstract

A brief review on unconventional oxygen-isotope (16O/18O) effects (OIE) in cuprate high-temperature superconductors (HTS) is presented. First the doping dependence of the OIE on the superconducting transition temperature TC in various HTS is discussed. For all cuprate HTS families the OIE exponent of TCO) shows a generic trend: In the underdoped regime αO is large (αO > 0.5) and becomes small in the optimally doped and overdoped regime. Magnetization, magnetic torque, and muon-spin rotation OIE studies of the in-plane penetration depth λab(0) in doped La2-xSrxCuO4 and Y1-xPrxBa2Cu3O7-δ indicate a substantial oxygen-mass dependence of the quantity λab-2(0), proportional to the superfluid density ρs(0) which increases with reduced doping. Even at optimal doping, where the OIE on TC is small, a pronounced OIE on λab(0) is present [1]. Note that an OIE on the penetration depth is not expected for a conventional phonon-mediated superconductor (for which the Migdal adiabatic approximation holds). The oxygen-isotope shifts of TC and λab(0) exhibit a correlation that appears to be generic for various families of HTSC. Site-selective OIE investigations of Y1-xPrxBa2Cu3O7-δ clearly reveal that the planar oxygen atoms mainly contribute to the total OIE on TC as well as on λab(0) at all doping levels. These unusual isotope effects strongly suggest that lattice effects play an essential role in the basic physics of cuprate HTS and have to be considered in any realistic theoretical model.
[1] R. Khasanov et al., Phys. Rev. Lett. 92, 057602-1 (2004).

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: http://science24.com/paper/2243 must be provided.

 

Related papers
  1. LnFeAsO single crystals grown at high pressure: influence of doping and substitutions on superconducting properties and structure

Presentation: invited oral at E-MRS Fall Meeting 2004, Plenary session, by Hugo Keller
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-22 11:24
Revised:   2009-06-08 12:55
Google
 
Web science24.com
© 1998-2022 pielaszek research, all rights reserved Powered by the Conference Engine