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Study of the triangular lattice tV model near x = (1/3)

Motrunich, O. I. and Lee, Patrick A. (2004) Study of the triangular lattice tV model near x = (1/3). Physical Review B, 70 (2). Art. No. 024514. ISSN 0163-1829. http://resolver.caltech.edu/CaltechAUTHORS:MOTprb04b

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Abstract

We study the extended Hubbard model on a triangular lattice near doping x = (1/3), which may be relevant for the recently discovered superconductor NaxCoO2·yH2O. By generalizing this model to N fermionic species, we formulate a meanfield description in the limit of large N. In meanfield, we find two possible phases: a renormalized Fermi liquid and a sqrt(3)×sqrt(3) charge density wave state. The transition between the two phases is driven by increasing the nearest-neighbor repulsion and is found to be first order for doping x = (1/3), but occurs close to the point of the local instability of the uniform liquid. We also study fluctuations about the uniform meanfield state in a systematic 1/N expansion, focusing on the residual interaction of quasiparticles and possible superconducting instabilities due to this interaction. Upon moving towards the charge density wave instability, the increasing charge fluctuations favor a particular f-wave triplet state. (This state was recently discussed by Tanaka et al., cond-mat/0311266.) We also report a direct Gutzwiller wave function study of the spin-(1/2) model.


Item Type:Article
Additional Information:©2004 The American Physical Society (Received 5 February 2004; published 22 July 2004) The authors thank Stuart Brown for bringing Ref. 7 to our attention. This work was supported by the National Science Foundation under Grant No. DMR-0201069. O.I.M. also wants to thank his family for support during his stay in Ukraine.
Subject Keywords:Hubbard model; doping; superconducting materials; sodium compounds; Fermi liquid; charge density waves; fluctuations in superconductors; wave functions; triplet state
Record Number:CaltechAUTHORS:MOTprb04b
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MOTprb04b
Alternative URL:http://dx.doi.org/10.1103/PhysRevB.70.024514
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7113
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:09 Jan 2007
Last Modified:26 Dec 2012 09:29

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