Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userInterplay between incommensurate phases in the cuprates
268
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We establish the qualitative behavior of the incommensurability $epsilon$, optimal domain wall filling $ u$ and chemical potential $mu$ for increasing doping by a systematic slave-boson study of an array of vertical stripes separated by up to $d=11$ lattice constants. Our findings obtained in the Hubbard model with the next-nearest neighbor hopping $t=-0.15t$ agree qualitatively with the experimental data for the cuprates in the doping regime $xlesssim 1/8$. It is found that $t$ modifies the optimal filling $ u$ and triggers the crossover to the diagonal (1,1) spiral phase at increasing doping, stabilized already at $xsimeq 0.09$ for $t=-0.3t$.
rate research
Read More
An electronic nematic phase can be classified by a spontaneously broken discrete rotational symmetry of a host lattice. In a square lattice, there are two distinct nematic phases. The parallel nematic phase breaks $x$ and $y$ symmetry, while the diagonal nematic phase breaks the diagonal $(x+y)$ and anti-diagonal $(x-y)$ symmetry. We investigate the interplay between the parallel and diagonal nematic orders using mean field theory. We found that the nematic phases compete with each other, while they coexist in a finite window of parameter space. The quantum critical point between the diagonal nematic and isotropic phases exists, and its location in a phase diagram depends on the topology of the Fermi surface. We discuss the implication of our results in the context of neutron scattering and Raman spectroscopy measurements on La$_{2-x}$Sr$_x$CuO$_4$.
Using a spin-rotation invariant version of the slave-boson approach we investigate the relative stability and band structure of various incommensurate phases in the cuprates. Our findings obtained in the Hubbard model with next-nearest neighbor hopping $-t/tsimeq 0.15$, as appropriate for the La$_{2-x}$Sr$_x$CuO$_4$ family, support the formation of diagonal (vertical) stripe phases in the doping regime $x=1/16$ ($x=1/8$), respectively. In contrast, based on the fact that a larger value $-t/t=0.3$ expected for YBa$_2$Cu$_3$O$_{6+delta}$ triggers a crossover to the diagonal (1,1) spiral phase at increasing doping, we argue that it might explain why the static charge order has been detected in YBa$_2$Cu$_3$O$_{6+delta}$ only in the highly underdoped regime.
The presence of incommensurate spiral spin-density waves (SDW) has been proposed to explain the $p$ (hole doping) to $1+p$ jump measured in the Hall number $n_H$ at a doping $p^*$. Here we explore {it collinear} incommensurate SDW as another possible explanation of this phenomenon, distinct from the incommensurate {it spiral} SDW proposal. We examine the effect of different SDW strengths and wavevectors and we find that the $n_Hsim p$ behavior is hardly reproduced at low doping. The calculated $n_H$ and Fermi surfaces give characteristic features that should be observed, thus the lack of these features in experiment suggests that the incommensurate collinear SDW is unlikely to be a good candidate to explain the $n_Hsim p$ observed in the pseudogap regime.
The nature of the state at low Landau-level filling factors has been a longstanding puzzle in the field of the fractional quantum Hall effect. While theoretical calculations suggest that a crystal is favored at filling factors $ ulesssim 1/6$, experiments show, at somewhat elevated temperatures, minima in the longitudinal resistance that are associated with fractional quantum Hall effect at $ u=$ 1/7, 2/11, 2/13, 3/17, 3/19, 1/9, 2/15 and 2/17, which belong to the standard sequences $ u=n/(6npm 1)$ and $ u=n/(8npm 1)$. To address this paradox, we investigate the nature of some of the low-$ u$ states, specifically $ u=1/7$, $2/13$, and $1/9$, by variational Monte Carlo, density matrix renormalization group, and exact diagonalization methods. We conclude that in the thermodynamic limit, these are likely to be incompressible fractional quantum Hall liquids, albeit with strong short-range crystalline correlations. This suggests a natural explanation for the experimentally observed behavior and a rich phase diagram that admits, in the low-disorder limit, a multitude of crystal-FQHE liquid transitions as the filling factor is reduced.
1$T$-TaSe$_{2}$ is host to coexisting strongly-correlated phases including charge density waves (CDWs) and an unusual Mott transition at low temperature. Here, we investigate coherent phonon oscillations in 1$T$-TaSe$_{2}$ using a combination of time- and angle-resolved photoemission spectroscopy (TR-ARPES) and time-resolved reflectivity (TRR). Perturbation by a femtosecond laser pulse triggers a modulation of the valence band binding energy at the $Gamma$-point, related to the Mott gap, that is consistent with the in-plane CDW amplitude mode frequency. By contrast, TRR measurements show a modulation of the differential reflectivity comprised of multiple frequencies belonging to the distorted CDW lattice modes. Comparison of the temperature dependence of coherent and spontaneous phonons across the CDW transition shows that the amplitude mode intensity is more easily suppressed during perturbation of the CDW state by the optical excitation compared to other modes. Our results clearly identify the relationship of the in-plane CDW amplitude mode with the Mott phase in 1$T$-TaSe$_{2}$ and highlight the importance of lattice degrees of freedom.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
