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TT: Tiefe Temperaturen
TT 14: Postersitzung II: Korrelierte Systeme(1-40), Theorie der Supraleitung(41-50), Metall-Isolator-Übergang, Lokalisierung(51-66), Niederdimensionale Systeme, Quantenhalleffekt(67-80), Pinning, kritische Ströme und Vortexdynamik(81-93), HTSL-Drähte und -Bänder(94-98), Massive HTSL(99-104), supraleitende Borkarbide(105-109)
TT 14.13: Poster
Mittwoch, 19. März 1997, 15:00–18:30, Z1
Magnetic excitations in CuGeO3 — •C. Gros1, V.N. Muthukumar1, W. Wenzel1, R. Valenti1, A. Fledderjohan2, P. Lemmens3, M. Fischer3, G. Güntherodt3, M. Weiden4, C. Geibel4, and F. Steglich4 — 1Institut f"ur Physik, Universität Dortmund, 44221 Dortmund — 2Institut f"ur Physik, Universität Wuppertal, 42097 Wuppertal — 33. Physikalisches Institut, RWTH Aachen, 52056 Aachen — 4FB Technische Physik, TH-Darmstadt, Hochschulstr. 8, 64289 Darmstadt
.
We discuss various aspects of the magnetic excitation spectrum
of the spin-Peierls compound CuGeO3. We present
analytic results, from a solitonic mean-field theory and
numerical data obtained from chains with up to 28 sites.
A detailed comparison with the experimental Raman and
Brillouin spectrum as a function of temperature and doping is
presented. We find:
(i) The magnetic Raman scattering is frustration induced
for T>TSP.
(ii) A novel dimerization of the Raman-operator for
T<TSP.
(iii) A dimensional crossover
from quasi 1D (for T>TSP) to quasi 2D
(for T<TSP) behaviour.
(iv) Numerical evidence for a bound two-spinon
state below the continuum in the dimerized state.
(v) No numerical support for an isolated two-magnon
bound-state in the dimerized phase.
(vi) A substantial reduction of the Raman-gap ΔR
with respect to twice the single magnon gap ΔS
(as measured by neutron scattering).