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Large Fermi surface and nanoscale phase separation in cuprates

Artur Maciąg 1Piotr Wróbel 1Robert Eder 2

1. Polish Academy of Sciences, Institute of Low Temperature and Structure Research (INTiBS), Okólna 2, Wrocław 50-422, Poland
2. Forschungszentrum Karlsruhe (FZK), Wolfgang-Gaede-Str. 1, Karlsruhe D-76131, Germany


Assuming that stripes in doped antiferromagnets take a form of two leg ladder-like structures which separate antiferromagnetic domains with opposite direction of the staggered magnetization and assuming that spin Peierls order forms on rungs, we calculate the spectral function of a hole propagating in such a system. In the case of a ladder, longitudinal propagation of a hole may be described in terms of a position exchange between a single hole and a singlet on neighboring rungs. This is a first order process. Propagation of a hole in an antiferromagnetic background, on the contrary, is mediated by a third order process which involves twice the action of the hopping term and once the action of the exchange term in the model Hamiltonian, which is the t-J model. A hopping hole creates linear defects in the antiferromagnetic spin background. Defects are removed if a hole retraces a path along which it has previously moved. Since hopping processes are much faster than processes related to the exchange interaction (t>>J) a strong tendency towards confinement by linear defects manifests and the system may be described in terms of quasi-localized spin polarons. Hopping of these objects is mediated by above mentioned high order processes. An effective tight binding Hamiltonian for a quasiparticle propagating in the stripe background is a combination of a model for a bare hole propagating in the ladder-like domain walls and a model for a propagating spin polaron in antiferromagnetic domains. By adding contributions to the spectral function from horizontal and vertical stripes we obtain a pattern which is in qualitative agreement with the Fermi surface identified in a doped LSCO system at 1/8 hole filling by means of ARPES measurements.


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Presentation: poster at E-MRS Fall Meeting 2004, Symposium E, by Artur Maciąg
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-27 12:08
Revised:   2009-06-08 12:55