Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userWeak phase separation and the pseudogap in the electron-doped cuprates
107
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We study the quantum transition from an antiferromagnet to a superconductor in a model for electron- and hole-doped cuprates by means of a variational cluster perturbation theory approach. In both cases, our results suggest a tendency towards phase separation between a mixed antiferromagnetic-superconducting phase at low doping and a pure superconducting phase at larger doping. However, in the electron-doped case the energy scale for phase separation is an order of magnitude smaller than for hole doping. We argue that this can explain the different pseudogap and superconducting transition scales in hole- and electron-doped materials.
rate research
Read More
Within the microscopic theory of the normal-state pseudogap state, the doping and temperature dependence of the charge dynamics in doped cuprates is studied in the whole doping range from the underdoped to heavily overdoped. The conductivity spectrum in the underdoped and optimally doped regimes contains the low-energy non-Drude peak and unusual midinfrared band. However, the position of the midinfrared band shifts towards to the low-energy non-Drude peak with increasing doping. In particular, the low-energy non-Drude peak incorporates with the midinfrared band in the heavily overdoped regime, and then the low-energy Drude behavior recovers. It is shown that the striking behavior of the low-energy non-Drude peak and unusual midinfrared band in the underdoped and optimally doped regimes is closely related to the emergence of the doping and temperature dependence of the normal-state pseudogap.
Electron interactions are pivotal for defining the electronic structure of quantum materials. In particular, the strong electron Coulomb repulsion is considered the keystone for describing the emergence of exotic and/or ordered phases of quantum matter as disparate as high-temperature superconductivity and charge- or magnetic-order. However, a comprehensive understanding of fundamental electronic properties of quantum materials is often complicated by the appearance of an enigmatic partial suppression of low-energy electronic states, known as the pseudogap. Here we take advantage of ultrafast angle-resolved photoemission spectroscopy to unveil the temperature evolution of the low-energy density of states in the electron-doped cuprate Nd$_{text{2-x}}$Ce$_{text{x}}$CuO$_{text{4}}$, an emblematic system where the pseudogap intertwines with magnetic degrees of freedom. By photoexciting the electronic system across the pseudogap onset temperature T*, we report the direct relation between the momentum-resolved pseudogap spectral features and the spin-correlation length with an unprecedented sensitivity. This transient approach, corroborated by mean field model calculations, allows us to establish the pseudogap in electron-doped cuprates as a precursor to the incipient antiferromagnetic order even when long-range antiferromagnetic correlations are not established, as in the case of optimal doping.
We report magnetoresistance and Hall Effect results for electron-doped films of the high-temperature superconductor La$_{2-x}$Ce$_x$CuO$_4$ (LCCO) for temperatures from 0.7 to 45 K and magnetic fields up to 65 T. For x = 0.12 and 0.13, just below the Fermi surface reconstruction (FSR), the normal state in-plane resistivity exhibits a well-known upturn at low temperature. Our new results show that this resistivity upturn is eliminated at high magnetic field and the resistivity becomes linear-in-temperature from $sim$ 40 K down to 0.7 K. The magnitude of the linear coefficient scales with Tc and doping, as found previously [1,2] for dopings above the FSR. In addition, the normal state Hall coefficient has an unconventional field dependence for temperatures below 50K. This anomalous transport data presents a new challenge to theory and suggests that the strange metal normal state is also present in the antiferromagnetic regime.
We study a two-dimensional model of an isolated narrow topological band at partial filling with local attractive interactions. Numerically exact quantum Monte Carlo calculations show that the ground state is a superconductor with a critical temperature that scales nearly linearly with the interaction strength. We also find a broad pseudogap regime at temperatures above the superconducting phase that exhibits strong pairing fluctuations and a tendency towards electronic phase separation; introducing a small nearest neighbor attraction suppresses superconductivity entirely and results in phase separation. We discuss the possible relevance of superconductivity in this unusual regime to the physics of flat band moir{e} materials, and as a route to designing higher temperature superconductors.
We present a self-consistent RVB theory which unifies the metallic (superconducting) phase with the half-filling antiferromagnetic (AF) phase. Two crucial factors in this theory include the RVB condensation which controls short-range AF spin correlations and the phase string effect introduced by hole hopping as a key doping effect. We discuss both the uniform and non-uniform mean-field solutions and show the unique features of the characteristic spin energy scale, superconducting transition temperature, and the phase diagram, which are all consistent with the experimental measurements of high-$T_c$ cuprates.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
