2003/09/10 by W. Kim, Wonkee Kim, J. P. Carbotte +1
Materials Science · Physics and Astronomy · #Classical XY model #Condensed matter physics #Cuprate #Hamiltonian (control theory) #Hubbard model #Kosterlitz–Thouless transition #Lattice (music) #Organic and Molecular Conductors Research #Phase transition #Physics #Physics of Superconductivity and Magnetism #Pseudogap #Quantum and electron transport phenomena #Quantum mechanics #Superconductivity #cond-mat.supr-con
paper · pdf · doi:10.1023/b:jolt.0000024550.59637.c2
3 figures
arxiv created 2003/09/10 · openalex publication_date 2004/04/21 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Based on an attractive U Hubbard model on a lattice with up to second neighbor hopping we derive an effective Hamiltonian for phase fluctuations. The superconducting gap is assumed to have s-wave symmetry. The effective Hamiltonian we finally arrive at is of the extended XY type. While it correctly reduces to a simple XY in the continuum limit, in the general case, it contains higher neighbor interaction in spin space. An important feature of our Hamiltonian is that it gives a much larger fluctuation region between the Berezinskii-Kosterlitz-Thouless transition temperature identified with Tc for superconducting and the mean field transition temperature identified with the pseudogap temperature.