Spatial dichotomy of quasiparticle dynamics in underdoped thin-filmYBa2Cu3O7−δsuperconductors

Abstract

By the spatial-temporal-resolved femtosecond spectroscopy on well-textured ͑110͒and ͑100͒-YBCO thin films, two distinctly temperature-dependent characteristics of quasiparticle relaxation in the nodal and antinodal directions are clearly identified. One temperature dependence associated with a high-energy gap has been observed along the ab diagonal for the whole hole-doping region and along the b axis except near optimal doping, while the other temperature dependence related to the opening of the superconducting gap appears along b axis regardless of the hole concentration. This spatial dichotomy between the nodal and antinodal quasiparticle dynamics and the evolution of gap symmetry with hole doping are discussed for enlightenment on the nature of the phase diagram of hole-doped cuprates. These strongly suggest that the two characteristics may have different physical origins and compete with each other.

Unveiling the hidden nematicity and spin subsystem in FeSe

“…In the literature, this difference is known to manifest the nematicity of the electronic structure. For example, the anisotropic single-particle and collective excitations in the quasi-1D charge-density wave semiconductor K 0.3 MoO 3 37 and the d-wave symmetry of the superconducting gap in cuprate superconductors YBCO [38][39][40][41] have been unambiguously revealed by polarized pump-probe spectroscopy. As intriguingly, the orientation anisotropy is shown also in τ 1 (Fig.…”

“…The intensity and polarization (electric field, E) of pulses were adjusted with a λ/2 plate and polarizer. [38][39][40][41] Moreover, the penetration depth of FeSe is~24 nm for 400 nm and~30 nm for 800 nm, which are estimated from the skin depth of electromagnetic wave in metal, λ/4πk.…”

Rotational symmetry breaking inBi2Sr2CaCu2O8+δprobed by polarized femtosecond spectroscopy

“…The two types of excitations were characterized by distinct relaxation times, temperature dependencies, and/or sign of the optical signal, depending on the material, doping level, photoexcitation intensity, and the wavelengths of light used in the pump-probe experiments [6][7][8][9][10]. The dependence on the probe photon polarization of the two-component reflectivity dynamics has also been reported [11,12]. However, the absence of a fundamental understanding of the optical processes involved in pump-probe experiments so far prevented analysis of the symmetry of excitations or detailed theoretical analysis of the excitations on a microscopic level.…”

Doping dependence of the ultrafast electronic dynamics ofY1−xPrxBa2Cu3Luo1, Lo2, Su3 et al. 2010Phys. Rev. BSelf Cite7090View full textAdd to dashboardCite

“…In the case of YBa 2 Cu 3 O 7−␦ , the amplitude of the positive component in ⌬R / R rises dramatically near T c , suggesting the opening of the superconducting gap. [7][8][9][10][11][12] Earlier works have overlooked the significant change in the rather small and negative component that occurs well above T c . For comparison, the temperature T N ͓marked by an arrow in Fig.…”

“…7-10͒ and related to the appearing of the pseudogap above T c . 7, [10][11][12] Experiments that are performed in this study conclusively reveal the photoinduced excitations in the Nernst region as well as their evolutions with the delay time. Above T c , a drastic change in the amplitude of ⌬R / R was clearly observed.…”