•The inter-site hole-phonon (h−ph) interaction in cuprates are studied in an anti-ferromagnetic background for cuprates.•At negligible h−ph interaction spin polarons are formed.•Large to small, ...stable hole-polarons are formed for increasing h−ph interaction strength.•S1 hole-bipolarons are also formed.•Pure attraction between holes cannot explain the phenomena of h−ph interactions in cuprates.
The interaction of the doped holes with lattice vibrations in an antiferromagnetic (AF) background is studied using the t−J-Holstein model on an 8-site cluster with 2-holes by an exact method. The phonon mediated interactions between the holes at nearest-neighbor (NN) sites are considered. We have calculated the effective kinetic energy, hole-phonon and hole–hole correlations, two hole binding energy to study the nature and stability of various quasiparticles. At negligible to very weak hole-phonon (h−ph) couplings, the holes get dressed by the AF background forming spin-polarons. At weak to intermediate h−ph couplings, the holes are dressed by the phonon cloud forming large hole-polarons and/or nearly free hole-polarons. A narrow transition region is observed at intermediate h−ph coupling depending on phonon energy, which marks the formation of S1 hole-bipolarons and small-hole-polarons. At strong coupling regime, stable hole-bipolarons are formed which may lead to superconducting condensation. We also argue that these results cannot be completely reproduced by considering pure attraction between holes. Results show the relevance of inter-site h−ph coupling in high Tc cuprates.
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This paper presents a detailed study of the uniform motion of a Holstein polaron as it moves along a chain in a constant electric field. The calculations showed that, depending on the parameters of ...the system, the duration of the uniform motion of the polaron along the chain can reach tens and hundreds of Bloch periods for a given value of the electric field intensity. It is shown that in the process of the uniform motion, the macro-part of the polaron moves at a constant velocity, retaining its shape. At the same time, the low-density components of the polaron, which arise immediately when a constant electric field is instantaneously switched on, have their own internal dynamics and demonstrate characteristic elements of the Bloch oscillations, such as the period of Bloch oscillations and the maximum Bloch amplitude. It is shown that not only the velocity and duration of the uniform motion of the polaron, but also the characteristics of the low-density components of the polaron depend on the value of the electric field intensity.
•It was first showed that Bloch oscillations are observed in uniform polaron motion.•The duration of the uniform polaron motion in a constant electric field is finite.•With uniform polaron motion, the low-density components of the polaron are formed.•Low-density components of polaron shows the characteristics of Bloch oscillations.•Low-density components characteristics persists throughout the uniform motion.
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Capturing non-Markovian dynamics of open quantum systems is generally a challenging problem, especially for strongly interacting many-body systems. In this Letter, we combine recently developed ...non-Markovian quantum state diffusion techniques with tensor network methods to address this challenge. As a first example, we explore a Hubbard-Holstein model with dissipative phonon modes, where this new approach allows us to quantitatively assess how correlations spread in the presence of non-Markovian dissipation in a 1D many-body system. We find regimes where correlation growth can be enhanced by these effects, offering new routes for dissipatively enhancing transport and correlation spreading, relevant for both solid state and cold atom experiments.
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We study the impact of the Rashba spin-orbit coupling (RSOC) on the stability of charge-density wave (CDW) in systems with large electron-phonon coupling (EPC). Here, the EPC is considered in the ...framework of the Holstein model at the half-filled square lattice. We obtain the phase diagram of the Rashba-Holstein model using the Hartree-Fock mean-field theory, and identify the boundaries of the CDW and Rashba metal phases. We notice that the RSOC disfavors the CDW phase, driving the system to a correlated Rashba metal. Also, we employ a cluster perturbation theory (CPT) approach to investigate the phase diagram beyond the Hartree-Fock approximation. The quantum correlations captured by CPT indicate that the RSOC is even more detrimental to CDW than previously anticipated. That is, the Rashba metal region is observed to be expanded in comparison to the mean-field case. Additionally, we investigate pairing correlations, and the results further strengthen the identification of critical points.
In this paper we consider the incipient formation of the internal dynamics of a uniformly moving polaron in a polynucleotide chain subjected to a constant electric field. The calculations performed ...show that Bloch oscillations arising in the course of the polaron oscillatory motion along the chain do not completely disappear when the polaron's motion along the chain becomes uniform. When the polaron moves uniformly along the chain, Bloch oscillations are also observed, although in a slightly different form. It is shown that the shape of the electron density distribution in a polaron during its stationary motion in a constant electric field takes an explicit structure. In this case, such characteristics of Bloch oscillations as the period of Bloch oscillations and the maximum Bloch amplitude demonstrate low-density components of the polaron.
Dynamics of a one-dimensional Holstein molecular crystal model is investigated by making use of the hierarchical equations of motion (HEOM) introduced by Tanimura and Kubo J. Phys. Soc. Jpn. 1989, ...104, 101. Our extended, numerically exact HEOM approach is capable of treating exciton–phonon coupling in a nonperturbative manner and is applicable to any temperature. It is revealed that strong exciton phonon coupling leads to excitonic localization, while a large exciton transfer integral facilitates exciton transport. Temperature effects on excitonic scattering have also been examined. A proof of concept, our work also serves as a benchmark for future comparisons with other numerical approaches to Holstein polaron dynamics.
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Various regimes of a charge motion along a chain in a constant electric field are investigated. This motion is simulated on the basis of the Holstein model. Earlier studies demonstrate a possibility ...of a uniform motion of a charge in a constant electric field over very long distances. For small values of the electric field intensity a Holstein polaron can move at a constant velocity. As the electric field intensity increases, a charge motion acquires oscillatorily character, performing Bloch oscillations. Since the charge motion depends on the whole set of the system parameters the character of the motion depends not only on the value of the electric field intensity. Therefore, the electric field intensity for which the uniform motion takes place differs for chains with different parameters. The character of the charge motion and distribution is considered in chains with different values of the constant of coupling between the charge and the displacements of the chain. We showed that the values of the electric field intensity for which the regime of a charge motion changes are different in chains with different values of the coupling constant. We also demonstrated that for one and the same value of the electric field intensity, in chains with different values of the coupling constant either a uniform motion or an oscillatory motion, or a stationary polaron can be observed.
Theoretical studies suggest that Su-Schrieffer-Heeger-like electron-phonon (e-ph) interactions can mediate high-temperature bipolaronic superconductivity that is robust against repulsive ...electron-electron interactions. Here we present a comparative analysis of the pairing and competing charge/bond correlations in the two-dimensional Holstein and optical Su-Schrieffer-Heeger (SSH) models using numerically exact determinant quantum Monte Carlo. We find that the SSH interactions support light bipolarons and strong superconducting correlations out to relatively large values of the e-ph coupling λ and densities near half-filling, while the Holstein interaction does not due to the formation of heavy bipolarons and competing charge-density-wave order. We further find that the Holstein and SSH models have comparable pairing correlations in the weak coupling limit for carrier concentrations < n > <<1, where competing orders and polaronic effects are absent. These results support the proposal that SSH (bi)polarons can support superconductivity to larger values of λ in comparison to the Holstein polaron, but that the resulting Tc gains are small in the weak coupling limit. We also find that the SSH model's pairing correlations are suppressed after including a weak on-site Hubbard repulsion. Furthermore, these results have important implications for identifying and engineering bipolaronic superconductivity.
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Abstract
In this work, we consider the motion of a polaron in a polynucleotide Holstein molecular chain in a constant electric field. It is shown that the character of the polaron motion in the chain ...depends not only on the chosen parameters of the chain, but also on the initial distribution of the charge along the chain. It is shown that for a small set value of the electric field intensity and for fixed values of the chain parameters, changing only the initial distribution of the charge in the chain, it is possible to observe either a uniform movement of the charge along the chain, or an oscillatory mode of charge movement.
The Holstein Hamiltonian describes itinerant electrons whose site density couples to local phonon degrees of freedom. In the single-site limit, at half filling, the electron-phonon coupling results ...in a double-well structure for the lattice displacement, favoring empty or doubly occupied sites. In two dimensions and on a bipartite lattice in d ≥ 2, intersite hopping causes these doubly occupied and empty sites to alternate in a charge density wave (CDW) pattern when the temperature is lowered. Because a discrete symmetry is broken, this occurs in a conventional second-order transition at finite Tcdw. In this paper, we investigate the effect of changing the phonon potential energy to one with an intrinsic double-well structure even in the absence of electron-phonon coupling. While this aids in the initial process of pair formation, the implications for subsequent CDW order are nontrivial. One expects that, when the electron-phonon coupling is too strong, the double wells become deep and the polaron mass gets large, an effect which reduces Tcdw. Here, we show here the existence of regions of parameter space where the double-well potential, while aiding local pair formation, does so in a way which also substantially enhances long-range CDW order.
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