ﻻ يوجد ملخص باللغة العربية
High resolution measurements of superfluid density and broadband quasiparticle conductivity have been used to probe the low energy excitation spectrum of nodal quasiparticles in underdoped YBCO. Penetration depth is measured to temperatures as low as 0.05 K. Microwave conductivity is measured from 0.1 to 20 GHz and is a direct probe of zero-energy quasiparticles. The data are compared with predictions for a number of theoretical scenarios that compete with or otherwise modify pure d-wave superconductivity, in particular commensurate and incommensurate spin and charge density waves; d + i s and d + i d superconductivity; circulating current phases; and the BCS--BEC crossover. We conclude that the data are consistent with a pure d-wave state in the presence of a small amount of strong scattering disorder, and are able to rule out most candidate competing states either completely, or to a level set by the energy scale of the disorder, ~ 4 K. Commensurate spin and charge density orders, however, are not expected to alter the nodal spectrum and therefore cannot be excluded.
Arguably the most intriguing aspect of the physics of cuprates is the close proximity between the record high-Tc superconductivity (HTSC) and the antiferromagnetic charge-transfer insulating state driven by Mott-like electron correlations. These are
We report measurements of the temperature dependence of the magnetic penetration depth lambda(T) in non-centrosymmetric superconductor Re_3W. We employed two experimental techniques: extraction of lambda(T) from magnetic {em dc}-susceptibility, measu
We report quantum oscillations in underdoped YBa2Cu3O6.56 over a significantly large range in magnetic field extending from 24 to 101 T, enabling three well-spaced low frequencies at 440 T, 532 T, and 620 T to be clearly resolved. We show that a smal
The mystery of the normal state in the underdoped cuprates has deepened with the use of newer and complementary experimental probes. While photoemission studies have revealed solely `Fermi arcs centered on nodal points in the Brillouin zone at which
Fine questions our interpretation of unidirectional-stripes over bidirectional-checkerboard, and illustrates his criticism by simulating a momentum space structure consistent with our data and corresponding to a checkerboard-looking real space densit