Fermi arcs and isotope effect of the magnetic penetration depth in underdoped cuprates

R. Zeyher^1a and A. Greco²

¹ Max-Planck-Institut für Festkörperforschung - Heisenbergstrasse 1, D-70569 Stuttgart, Germany, EU
² Departamento de Física, Facultad de Ciencas Exactas e Ingeniería and IFIR (UNR-CONICET) Av. Pellegrini 250, 2000 Rosario, Argentina

^a R.Zeyher@fkf.mpg.de

Received: 26 December 2010
Accepted: 16 February 2011

Abstract

The isotope coefficient β of the magnetic penetration depth in the superconducting state is studied at T=0 for a d-CDW and a nodal metal model. Disregarding superconductivity the Fermi surface of the first model possesses arcs whereas the second model has no arcs.We show that a large increase of β in the pseudogap region is generically incompatible with Fermi arcs in the pseudogap state. Thus only the second model shows a large increase of β with decreasing doping. The required electron-phonon coupling is small and compatible with first-principles calculations based on the local density approximation (LDA).