Polarized and unpolarized triple-axis neutron measurements were performed on an underdoped crystal of YBa2Cu3O7-x (x = 0.4 ± 0.02, Tc = 62.7 K). Our results indicate, contrary to earlier evidence, that the spin excitations in the superconducting state are essentially the same as those in the fully doped material except that the unusual 41 meV resonance is observed at 34.8 meV. The normal state spin excitations are characterized by a weakly energy-dependent continuum whose temperature dependence shows the clear signature of a superconducting gap at Tc. The enhancement at the resonance is accompanied by a suppression of magnetic fluctuations at both higher and lower energies.
P. Dai et al., "Magnetic Dynamics in Underdoped YBa2Cu3O7-x: Direct Observation of a Superconducting Gap," Physical Review Letters, vol. 77, no. 27, pp. 5425-5428, American Physical Society (APS), Dec 1996.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevLett.77.5425
Materials Science and Engineering
Keywords and Phrases
Magnetic permeability; Magnetization; Neutron scattering; Phonons; Resonance; Single crystals; Spectrometers; Thermal effects; Continuum mechanics; Crystals; Doping (additives); Energy gap; Fermi level; Polarization; Oxygenation; Spin excitations; Superconducting gap; Yttrium barium copper oxide; Yttrium compounds; Oxide superconductors; Gap functions; Superconducting gaps; Twinned disks; Underdoped crystals
International Standard Serial Number (ISSN)
Article - Journal
© 1996 American Physical Society (APS), All rights reserved.