Abstract
We study the effects of charge degrees of freedom on the spin excitation dynamics in quasi-one-dimensional magnetic materials. Using the density matrix renormalization group method, we calculate the dynamical spin structure factor of the Hubbard model at half electronic filling on a chain and on a ladder geometry, and compare the results with those obtained using the Heisenberg model, where charge degrees of freedom are considered frozen. For both chains and two-leg ladders, we find that the Hubbard model spectrum qualitatively resembles the Heisenberg spectrum - with low-energy peaks resembling spinonic excitations - already at intermediate on-site repulsion as small as U/t∼2-3, although ratios of peak intensities at different momenta continue evolving with increasing U/t converging only slowly to the Heisenberg limit. We discuss the implications of these results for neutron scattering experiments and we propose criteria to establish the values of U/t of quasi-one-dimensional systems described by one-orbital Hubbard models from experimental information.
Original language | English |
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Article number | 205145 |
Journal | Physical Review B |
Volume | 94 |
Issue number | 20 |
DOIs | |
State | Published - Nov 28 2016 |
Funding
This work was conducted at the Center for Nanophase Materials Sciences, sponsored by the Scientific User Facilities Division (SUFD), BES, DOE, under contract with UT-Battelle. A.N. and G.A. acknowledge support by the Early Career Research program, SUFD, BES, DOE. N.P. and E.D. were supported by the National Science Foundation (NSF) under Grant No. DMR-1404375. N.P. was also partially supported by the U.S. Department of Energy (DOE), Office of Basic Energy Science (BES), Materials Science and Engineering Division. Research at ORNL's HFIR and SNS (J.F.-B.) was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.