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arXiv · 1412.0287

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

Marcin Raczkowski·Fakher F. Assaad·Lode Pollet
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Abstract

We use quantum Monte Carlo simulations to study a finite-temperature dimensional-crossover-driven evolution of spin and charge dynamics in 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) 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 $\sigma_{\perp}(\omega)$ implies the onset of a higher-dimensional metal. In this metallic phase, enhanced quasiparticle scattering off finite-range AF fluctuations results in incoherent single-particle dynamics. The coupling between spin and charge fluctuations is also seen in the spin dynamical structure factor $S({\pmb q},\omega)$ displaying damped spin excitations (paramagnons) close to the AF wave-vector ${\pmb q}=(\pi,\pi)$ 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.

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Marcin Raczkowski, Fakher F. Assaad, Lode Pollet. 2014-11-30. Spin and charge dynamics of a quasi-one-dimensional antiferromagnetic metal. https://doi.org/10.1103/physrevb.91.045137

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