Visualization of electronic structures in the two-dimensional Hubbard model--Spinons, polarons, and stripes

摘要

Quantum fluctuations (QFs) in the two-dimensional Hubbard model are visualized by using a resonating Hartree-Fock method. Wave functions of optimized multi-Slater determinants show that QFs in the half-filled system are described by vibration, translation, and rotation of spinon-antispinon pairs, while those motions of polarons constitute dominant QFs in the lightly doped systems. We show that an attractive interaction works between two polarons in the framework of a projected Hartree-Fock approximation. The ground states at about 10% doping have a stripe structure and Q's due to deviations from a uniform stripe.