arXiv subjects

Da-Wei Yao

Publications and source records attributed to Da-Wei Yao.

6 recordsLinked to original sources

arXiv2025

Model-independent Test of the Cosmic Anisotropy with Inverse Distance Ladder

If the Universe is endowed with cosmic anisotropy, it will have a preferred direction of expansion. Reconstructing the expansion history by Gaussian Process (GP) can be used to probe the cosmic anisotropy model-independently. In this paper, for the luminosity distance $d_L(z)$ reconstruction, we turn to the inverse distance ladder, where type Ia supernova (SNIa) from the Pantheon+ sample determine relative distances and strongly gravitationally lensed quasars from H0LiCOW sample anchor these relative distances with some absolute distance measurements. By isolating the anisotropic information that could be carried by the Hubble constant $H_0$ and obtaining constraints on the intrinsic parameter of SNIa, the absolute magnitude $M=-19.2522^{+0.0594}_{-0.0649}$ (at $68\%$ CL), we find that $d_L(z)$ reconstructions from samples located in different region of the Galactic coordinate system are almost consistent with each other, while only a very weak preference for the cosmic anisotropy is found.

astro-ph.CO↗

arXiv2020

Why the anti-nodal quasiparticle dispersion is so flat in the superconducting cuprates?

The emergence of the coherent quasiparticle peak and the development of the peak-dip-hump structure in the anti-nodal region below $T_{c}$ is the most prominent non-BCS signature of the underdoped high-$T_{c}$ cuprates, in which no coherent quasiparticle can be defined in the anti-nodal region above $T_{c}$. The peak-dip-hump structure has been commonly interpreted as the result of the coupling of the electron to some Bosonic mode. However, such an electron-Boson coupling picture does not answer the question of \textit{why the quasiparticle dispersion is so flat in the anti-nodal region}, a behavior totally unexpected for Bogoliubov quasiparticle in a d-wave BCS superconductor. Here we show that the sharp quasiparticle peak in the anti-nodal region should be understood as a new pole in the electron Green's function generated by the strong coupling of the electron to diffusive spin fluctuation around the antiferromagnetic wave vector $\mathbf{Q}=(π,π)$, rather than a nearly free Bogoliubov quasiparticle in a d-wave BCS superconductor. More specifically, we find that the normal self-energy of the electron from the scattering with the diffusive spin fluctuation manifests itself mainly as a level repulsion effect and is responsible for the reduction of both the quasiparticle dispersion and the quasiparticle dissipation rate in the anti-nodal region. We argue that the peak-dip separation in the anti-nodal spectrum should not be interpreted as the energy of the pairing glue.

cond-mat.supr-con↗

arXiv2019

Detecting the orbital character of the spin fluctuation in the Iron-based superconductors with the resonant inelastic X-ray scattering spectroscopy

The orbital distribution of the spin fluctuation in the iron-based superconductors(IBSs) is the key information needed to understand the magnetism, superconductivity and electronic nematicity in these multi-orbital systems. In this work, we propose that the resonant inelastic X-ray scattering(RIXS) technique can be used to probe selectively the spin fluctuation on different Fe $3d$ orbitals. In particular, the spin fluctuation on the three $t_{2g}$ orbitals, namely, the $3d_{xz}$, $3d_{yz}$ and the $3d_{xy}$ orbital, can be selectively probed in the $σ\rightarrowπ'$ scattering geometry by aligning the direction of the outgoing photon in the $y$, $x$ and $z$ direction. Such orbital-resolved information on the spin fluctuation is invaluable for the study of the orbital-selective physics in the IBSs and can greatly advance our understanding on the relation between orbital ordering and spin nematicity in the IBSs and the orbital-selective pairing mechanism in these multi-orbital systems.

cond-mat.supr-con↗

arXiv2018

Vanishing pseudogap around $(π,0)$ in an electron-doped high-$\mathrm{T_{c}}$ superconductor: a simple picture

Recent ARPES measurement on electron-doped cuprate $\mathrm{Pr}_{1.3-x}\mathrm{La}_{0.7}\mathrm{Ce}_{x}\mathrm{CuO}_{4}$ finds that the pseudogap along the boundary of the antiferromagnetic Brillouin zone(AFBZ) exhibits dramatic momentum dependence. In particular, the pseudogap vanishes in a finite region around the anti-nodal point, in which a single broadened peak emerges at the un-renormalized quasiparticle energy. Such an observation is argued to be inconsistent with the antiferromagnetic(AFM) band-folding picture, which predicts a constant pseudogap along the AFBZ boundary. On the other hand, it is claimed that the experimental results are consistent with the prediction of the cluster dynamical mean field theory(CDMFT) simulation on the Hubbard model, in which the pseudogap is interpreted as a s-wave splitting between the Hubbard bands and the in-gap states. Here we show that the observed momentum dependence of the pseudogap is indeed consistent with AFM band-folding picture, provided that we assume the existence of a strongly momentum dependent quasiparticle scattering rate. More specifically, we show that the quasiparticle scattering rate acts to reduce the spectral gap induced by AFM band-folding effect. The new quasiparticle poles corresponding to the AF-split bands can even be totally eliminated when the scattering rate exceeds the bare band folding gap, leaving the system with a single pole at the un-renormalized quasiparticle energy. We predict that the pseudogap should close in a square root fashion as we move toward $(π,0)$ along the AFBZ boundary. Our results illustrates again that the quasiparticle scattering rate can play a much more profound role than simply broadening the quasiparticle peak in the quasiparticle dynamics of strongly correlated electron systems.

cond-mat.str-el↗

arXiv2018

The driving mechanism of the d-wave orbital order in the iron-based superconductors

We study the driving mechanism and the form of the orbital order in the electronic nematic phase of the iron-based superconductors(IBSs) within the random phase approximation of a 5-band model. We find the magnetic correlation energy of the system can be significantly improved when an orbital order of the d-wave form is spontaneously generated. On the other hand, the magnetic correlation energy increases as one introduce either an on-site or an extended s-wave orbital order. More specifically, we find that the on-site orbital order is disfavored by the Hund's rule coupling and the extended s-wave orbital order is disfavored by the stripy magnetic correlation pattern in the IBSs.

cond-mat.supr-con↗

arXiv2018

Pairing origin of the pseudogap as observed in ARPES measurement in the underdoped cuprates

We show that electron pairing is indispensable for the development of the leading edge gap as observed in ARPES measurement in the underdoped cuprates, even though clear evidence for the violation of the particle-hole symmetry is found in the electron spectrum. To support this assertion, we studied the electron spectrum under the scattering of diffusive antiferromagnetic(AF) spin fluctuation, which is thought to be a major candidate for a competing order in the competing order scenario of the pseudogap phenomena. We find that the Fermi level crossing along the M=$(π,0)$ to X=$(π,π)$ line can only be avoided when the M point is pushed above the Fermi level in this scenario. We argue that the same conclusion holds in all competing order scenarios that preserve the U(1) charge conservation. The inconsistency between this prediction and the ARPES observation implies that a competing order in the particle-hole channel alone is not sufficient to explain the pseudogap as observed in ARPES measurement. We also find that the electron system always forms a single large Fermi surface under the scattering of short-ranged dynamical spin fluctuation, rather than forming small Fermi pockets as predicted by the AF band folding picture. The AF shadow band is smeared out in energy as a result of the dispersion in the scattered quasiparticle state and the diffusion in spin fluctuation energy. Nevertheless, we find that the AF band folding effect is important for the understanding of the quasiparticle dynamics in the pseudogap phase, especially, of the origin of the high energy hump structure in the anti-nodal region and the signature of particle-hole asymmetry in the electron spectrum.

cond-mat.supr-con↗