Phononic and magnetic excitations in the quasi-one-dimensional Heisenberg antiferromagnet KCuF₃
The Raman-active phonons and magnetic excitations in the orbitally ordered, quasi-one-dimensional Heisenberg
 antiferromagnet KCuF₃ are studied as a function of temperature in the range between 3 and 290 K in various
 scattering configurations. The low-energy Eg and B1g phonon modes...
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| Published in: | Физика низких температур |
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| Date: | 2012 |
| Main Authors: | , , , , , , , |
| Format: | Article |
| Language: | English |
| Published: |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2012
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| Subjects: | |
| Online Access: | https://nasplib.isofts.kiev.ua/handle/123456789/117189 |
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| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | Phononic and magnetic excitations in the quasi-one-dimensional Heisenberg antiferromagnet KCuF₃ / V. Gnezdilov, J. Deisenhofer, P. Lemmens, D. Wulferding, O. Afanasiev, P. Ghigna, A. Loidl, A. Yeremenko // Физика низких температур. — 2012. — Т. 38, № 5. — С. 538-548. — Бібліогр.: 66 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| Summary: | The Raman-active phonons and magnetic excitations in the orbitally ordered, quasi-one-dimensional Heisenberg
antiferromagnet KCuF₃ are studied as a function of temperature in the range between 3 and 290 K in various
scattering configurations. The low-energy Eg and B1g phonon modes show an anomalous softening (~25%
and ~13%) between room temperature and the characteristic temperature TS = 50 K. In this temperature range a
freezing-in of F–
ion dynamic displacements is proposed to occur. In addition, the Eg mode at about 260 cm⁻¹
clearly splits below TS. The widths of the phonon lines above TS follow an activated behavior with an activation
energy of about 50 K. Our observations clearly evidence a reduction of the lattice symmetry below TS and indicate
a strong coupling of lattice, spin, and orbital fluctuations for T > TS. A strongly polarization dependent quasielastic
scattering is observed at temperatures above TN = 39 K due to magnetic-energy fluctuations. For temperatures
below TN a rich spectrum of additional modes is observed, with different lineshape, polarization and
temperatures dependence. We attribute them to longitudinal and transverse magnetic modes as well as to a continuum
of magnetic excitations.
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| ISSN: | 0132-6414 |