Flat-band ferromagnetism of SU(N) Hubbard model on Tasaki lattices

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2019,（20）
• 页码范围: 1490-1495
• 页数: 6页
• 语种: 英文

摘要

We investigate the para-ferro magnetic transition of the repulsive SU(N) Hubbard model on a type of one-and two-dimensional decorated cubic lattices,referred as Tasaki lattices,which feature massive singleparticle ground state degeneracy.Under certain restrictions for constructing localized many-particle ground states of fiat-band ferromagnetism,the quantum model of strongly correlated electrons is mapped to a classical statistical geometric site-percolation problem,where the nontrivial weights of different configurations must be considered.We prove rigorously the existence of para-ferro transition for the SU(N) Hubbard model on one-dimensional Tasaki lattice and determine the critical density by the transfer-matrix method.In two dimensions,we numerically investigate the phase transition of SU(3),SU(4) and SU(10) Hubbard models by Metropolis Monte Carlo simulation.We find that the critical density exceeds that of standard percolation,and increases with spin degrees of freedom,implying that the effective repulsive interaction becomes stronger for larger N.We further rigorously prove the existence of fiat-band ferromagnetism of the SU(N) Hubbard model when the number of particles equals to the degeneracy of the lowest band in the single-particle energy spectrum.