Electron-phonon Driven Spin Frustration in Multi-band Hubbard Models: Mx Chains and Oxide Superconductors
نویسنده
چکیده
We discuss the consequences of both electron-phonon and electron-electron couplings in 1D and 2D multi-band (Peierls-Hubbard) models. After briefly discussing various analytic limits, we focus on (Hartree-Fock and exact) numerical studies in the intermediate regime for both couplings, where unusual spin-Peierls as well as long-period, frustrated ground states are found. Doping into such phases or near the phase boundaries can lead to further interesting phenomena such as separation of spin and charge, a dopant-induced phase transition of the global (parent) phase, or real-space (“bipolaronic”) pairing. We discuss possible experimentally observable consequences of this rich phase diagram for halogen-bridged, transition metal, linear chain complexes (MX chains) in 1D and the oxide superconductors in 2D.
منابع مشابه
Metallicity in the half-filled Holstein-Hubbard model
We re-examine the Peierls insulator to Mott insulator transition scenario in the one-dimensional Holstein-Hubbard model where, at half-filling, electron-phonon and electron-electron interactions compete for establishing chargeand spin-density-wave states, respectively. By means of large-scale density-matrix renormalization group calculations we determine the spin, single-particle and two-partic...
متن کاملادغام الگوی شبکهای هولشتاین - کاندو برای توصیف نظریه ابررساناهای دمای بالا
It is a common knowledge that the formation of electron pairs is a necessary ingredient of any theoretical work describing superconductivity. Thus, finding the mechanism of the formation of the electron pairs is of utmost importance. There are some experiments on high transition temperature superconductors which support the electron-phonon (e-ph) interactions as the pairing mechanism (ARPES),...
متن کاملOne-electron bands, quantum Monte Carlo, and real superconductors
We use the doped Fullerenes as an example of how realistic systems can be described by simple models. Starting from the band structure we set up a tight-binding model that describes the t1u conduction band. Adding correlation terms we arrive at a generalized Hubbard Hamiltonian that we treat using quantum Monte Carlo. To address the problem of superconductivity in the doped Fullerenes, we study...
متن کاملBipolaron density-wave driven by antiferromagnetic correlations and frustration in organic superconductors
We describe the paired electron crystal (PEC) which occurs in the interacting frustrated twodimensional 4filled band. The PEC is a charge-ordered state with nearest-neighbor spin singlets separated by pairs of vacant sites, and can be thought of as a bipolaron density wave. The PEC has been experimentally observed in the insulating state proximate to superconductivity in the organic chargetrans...
متن کاملDimerization and Entanglement in Spin-Orbital Chains
Spin-orbital coupling: The study of orbital degeneracy in transition metal oxides is motivated, e.g., by the large variety of spin-charge-orbital ordered phases, the possible control of the orbital degree of freedom at interfaces and heterostructures, the switching from orbital ordered to metallic phases in applied magnetic fields, and the colossal magnetoresistance. The rather complex interpla...
متن کامل