Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSlave fermion approach to the metallic phase in large $U_d$ high-T$_c$ cuprates
127
0
0.0
(
0
)
Added by
O. S. Bari\\v{s}i\\'c
Publication date
2008
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Atomic repulsion $U_d$ on the Cu site in high T$_c$ cuprates is large but, surprisingly, some important properties are consistent with moderate couplings. The time dependent perturbation theory with slave particles is therefore formulated in the $U_dtoinfty$ limit for the metallic phase in the physically relevant regime of the three-band Emery model. The basic theory possesses the local gauge invariance asymptotically but its convergence is fast when the average occupation of the Cu-site is small. The leading orders exhibit the band narrowing and the dynamic Cu/O$_2$ charge transfer disorder. The effective local repulsion between particles on oxygen sites is shown to be moderate in the physical regime under consideration. It enhances the coherent incommensurate SDW correlations. The latter compete with the Cu/O$_2$ charge transfer disorder, in agreement with basic observations in high T$_c$ cuprates.
rate research
Read More
We investigate the hole dynamics in two prototypical high temperature superconducting systems: La$_{2-x}$Sr$_{x}$CuO$_{4}$ and YBa$_{2}$Cu$_{3}% $O$_{y}$ using a combination of DC transport and infrared spectroscopy. By exploring the effective spectral weight obtained with optics in conjunction with DC Hall results we find that the transition to the Mott insulating state in these systems is of the vanishing carrier number type since we observe no substantial enhancement of the mass as one proceeds to undoped phases. Further, the effective mass remains constant across the entire underdoped regime of the phase diagram. We discuss the implications of these results for the understanding of both transport phenomena and pairing mechanism in high-T$_{c}$ systems.
Using a rotationally invariant version of the slave-boson approach in spin space we analyze the stability of stripe phases with large unit cells in the two-dimensional Hubbard model. This approach allows one to treat strong electron correlations in the stripe phases relevant in the low doping regime, and gives results representative of the thermodynamic limit. Thereby we resolve the longstanding controversy concerning the role played by the kinetic energy in stripe phases. While the transverse hopping across the domain walls yields the largest kinetic energy gain in the case of the insulating stripes with one hole per site, the holes propagating along the domain walls stabilize the metallic vertical stripes with one hole per two sites, as observed in the cuprates. We also show that a finite next-nearest neighbor hopping $t$ can tip the energy balance between the filled diagonal and half-filled vertical stripes, which might explain a change in the spatial orientation of stripes observed in the high $T_c$ cuprates at the doping $xsimeq 1/16$.
We demonstrate that the strong anomalies in the high frequency LO-phonon spectrum in cuprate superconductors can in principle be explained by the enhanced electronic polarizability associated with the self-organized one dimensionality of metallic stripes. Contrary to the current interpretation in terms of transversal stripe fluctuations, the anomaly should occur at momenta parallel to the stripes. The doping dependence of the anomaly is naturally explained, and we predict that the phonon line-width and the spread of the anomaly in the transverse momentum decrease with increasing temperature while high resolution measurements should reveal a characteristic substructure to the anomaly.
We develop a novel self-consistent approach for studying the angle resolved photoemission spectra (ARPES) of a hole in the t-J-Holstein model giving perfect agreement with numerically exact Diagrammatic Monte Carlo data at zero temperature for all regimes of electron-phonon coupling. Generalizing the approach to finite temperatures we find that the anomalous temperature dependence of the ARPES in undoped cuprates is explained by cooperative interplay of coupling of the hole to magnetic fluctuations and strong electron-phonon interaction.
High-$T_c$ superconductors with CuO$_2$ layers, manganites La$_{1-x}$Sr$_x$MnO$_3$, and cobaltites LaCoO$_3$ present several mysteries in their physical properties. Most of them are believed to come from the strongly-correlated nature of these materials. From the theoretical viewpoint, there are many hidden rocks in making the consistent description of the band structure and low-energy physics starting from the Fermi-liquid approach. Here we discuss the alternative method -- multielectron approach to the electronic structure calculations for the Mott insulators -- called LDA+GTB (local density approximation + generalized tight-binding) method. Its origin is a straightforward generalization of the Hubbard perturbation theory in the atomic limit and the multiband $p-d$ Hamiltonian with the parameters calculated within LDA. We briefly discuss the method and focus on its applications to cuprates, manganites, and cobaltites.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
