On the Kinetic Energy Driven Superconductivity in the Two-Dimensional Hubbard Model

• Published in: Condensed matter 2021-03, Vol.6 (1), p.12
• Main Authors: Yanagisawa, Takashi, Yamaji, Kunihiko, Miyazaki, Mitake
• Format: Article
• Language: English
• Subjects: Correlation; Dimensional stability; Energy; High temperature; high-temperature superconductor; Hubbard model; Kinetic energy; mechanism of superconductivity; Monte Carlo simulation; Optimization; optimization variational Monte Carlo method; Physics; strongly correlated electrons; Superconductivity; Symmetry; Two dimensional models; two-dimensional Hubbard model; Wave functions
• ISSN: 2410-3896; 2410-3896
• DOI: 10.3390/condmat6010012

We investigate the role of kinetic energy for the stability of superconducting state in the two-dimensional Hubbard model on the basis of an optimization variational Monte Carlo method. The wave function is optimized by multiplying by correlation operators of site off-diagonal type. This wave function is written in an exponential-type form given as ψλ=exp(−λK)ψG for the Gutzwiller wave function ψG and a kinetic operator K. The kinetic correlation operator exp(−λK) plays an important role in the emergence of superconductivity in large-U region of the two-dimensional Hubbard model, where U is the on-site Coulomb repulsive interaction. We show that the superconducting condensation energy mainly originates from the kinetic energy in the strongly correlated region. This may indicate a possibility of high-temperature superconductivity due to the kinetic energy effect in correlated electron systems.