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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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.
|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|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||09 Jan 2007|
|Last Modified:||26 Dec 2012 09:29|
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