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Title:
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Evidence for decay of spin waves above the pseudogap of underdoped YBa2Cu3O6.35 |
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Author:
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Stock, C.; Cowley, R.A.; Buyers, W.J.L.; Coldea, R.; Broholm, C.; Frost, C.D.; Birgeneau, R.J.; Liang, R.; Bonn, D.; Hardy, W.N. |
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Abstract:
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The magnetic spectrum at high energies in heavily underdoped YBa2Cu3O6.35 (Tc=18 K) has been determined throughout the Brillouin zone. At low energy, the scattering forms a cone of spin excitations emanating from the antiferromagnetic (0.5,0.5) wave vector with an acoustic velocity similar to that of insulating cuprates. At high-energy transfers, below the maximum energy of 270 meV at (0.5,0), we observe zone-boundary dispersion much larger and spectral weight loss more extensive than in insulating antiferromagnets. Moreover, we report phenomena not found in insulators, an overall lowering of the zone-boundary energies and a large damping of ~100 meV of the spin excitations at high energies. The energy above which the damping occurs coincides approximately with the gap determined from transport measurements. We propose that as the energy is raised, the spin excitations encounter an extra channel of decay into particle-hole pairs of a continuum that we associate with the pseudogap. |
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URI:
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http://jhir.library.jhu.edu/handle/1774.2/33748
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Date:
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2007-05-01 |
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Citation:
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Physical Review B (Condensed Matter and Materials Physics) 1 May 2007, vol.75, no.17, pp.
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Subject:
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energy transfers
insulating cuprates
acoustic velocity
antiferromagnetic wave vector
spin-wave decay
spectral weight loss
spin excitations
low-energy the scattering
Brillouin zone
spin-wave decay
insulating antiferromagnets
zone-boundary energies
yttrium compounds
spin waves
high-temperature superconductors
barium compounds
acoustic wave velocity
damping
particle-hole pairs
YBa2Cu3O6.35
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