Spin and charge dynamics of a quasi-one-dimensional antiferromagnetic metal

Abstract

We use quantum Monte Carlo simulations to study a finite-temperature dimensional-crossoverdriven evolution of spin and charge dynamics in an anisotropic two-dimensional system of weakly coupled Hubbard chains with a half-filled band. The low-temperature behavior of the charge gap indicates a crossover between two distinct energy scales: a high-energy one-dimensional (1D) Mott gap due to the umklapp process and a low-energy gap which stems from long-range antiferromagnetic (AF) spin fluctuations. Away from the 1D regime and at temperature scales above the charge gap, the emergence of a zero-frequency Drude-like feature in the interchain optical conductivity σ ⊥ (ω) implies the onset of a higher-dimensional metal. In this metallic phase, enhanced quasiparticle scattering off finite-range AF spin fluctuations results in incoherent single-particle dynamics. The coupling between spin and charge fluctuations is also seen in the spin dynamical structure factor S(q q q, ω) displaying damped spin excitations (paramagnons) close to the AF wave-vector q q q = (π, π) and particle-hole continua near 1D momentum transfers spanning quasiparticles at the Fermi surface. We relate our results to the charge deconfinement in quasi-1D organic Bechgaard-Fabre salts.

Polarization dependence of angle-resolved photoemission with submicron spatial resolution reveals emerging one-dimensionality of electrons in NbSe3

“…Thus new possibilities for arise in a quasi-one-dimensional material. If the hopping between one-dimensional entities, which will be discussed below, is small compared to the inverse timescale of the ARPES process t ⊥ t <hω, hopping in the direction perpendicular to the chains is essentially incoherent [16,17,56]. In this high-energy limit the electron liquid is then in a 1D regime.…”

Mott Quantum Criticality in the Anisotropic 2D Hubbard Model

“…We believe that this scenario is not restricted to quantum cluster descriptions of the system but should also emerge in lattice simulations, provided that the range of AFM spin fluctuations is reduced, e.g., by geometrical frustration or disorder [56,57]. This leads, however, to a severe sign problem which renders lattice QMC simulations very expensive [58]. In this respect, a promising route avoiding the main shortcomings of QMC is offered by tensor network methods [59] adapted recently to fermionic systems [60,61].…”

One-particle spectral functions of the one-dimensional Fermionic Hubbard model with one fermion per site at zero and finite magnetic fields

“…4-6) and low m values (Figs. [13][14][15][16][17][18], the momentum dependent exponents are little u dependent, the same applying to the s branch-line exponents (Figs. 15,18) for all spin densities.…”

“…For electrons, the one-particle spectral function describes at zero field spectral-weight distributions that can be accessed by angle-resolved photoemission spectroscopy (ARPES) [13][14][15] in low-dimensional Mott-Hubbard insulators and corresponding doped insulators 16 . 1D Mott-Hubbard insulators can be studied within condensed matter by inelastic neutron scattering in spin chains whose charge degrees of freedom are gapped, as well as a number of quasi-1D organic compounds 17 .…”