2006/06/26 by Massimo Lugas, Leonardo Spanu, Federico Becca +1 · 36 citations
Mathematics · Physics and Astronomy · #Algorithm #Ansatz #Antiferromagnetism #Charge (physics) #Compressibility #Condensed matter physics #Function (biology) #Hubbard model #Materials science #Mathematical physics #Mathematics #Order (exchange) #Phase (matter) #Physics #Physics of Superconductivity and Magnetism #Projection (relational algebra) #Quantum and electron transport phenomena #Quantum many-body systems #Quantum mechanics #Range (aeronautics) #Spin (aerodynamics) #Superconductivity #Thermodynamics #Variational Monte Carlo #Wave function #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.74.165122
published in Physical Review B 74(16) (American Physical Society) · 10 pages
arxiv created 2006/06/26 · openalex publication_date 2006/10/31 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We reexamine the important issue of charge fluctuations in the two-dimensional t\text\ensuremath-J model by using an improved variational method based on a wave function that contains both antiferromagnetic and d-wave superconducting order parameters. In particular, we generalize the wave function introduced some time ago by Bouchaud, Georges, and Lhuillier [J. Phys. (Paris) 49, 553 (1988)] by considering also a long-range spin-spin Jastrow factor, in order to correctly reproduce the small-q behavior of the spin fluctuations. We mainly focus our attention on the physically relevant region J∕t\ensuremath∼0.4 and find that, contrary to a previous variational ansatz, this state is stable against phase separation for small hole doping. Moreover, by performing projection Monte Carlo methods based on the so-called fixed-node approach, we obtain clear evidence that the t\text\ensuremath-J model does not phase separate for J∕t\ensuremath\lesssim0.7 and that the compressibility remains finite close to the antiferromagnetic insulating state.