Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 55: Poster II
MA 55.46: Poster
Freitag, 4. April 2014, 10:30–13:30, P2
Dispersive Magnon Excitations in Ca3Co2O6 — •Pavlo Y. Portnichenko2, Anil Jain1, Hoyoung Jang1, Alexandr Ivanov3, Bernhard Keimer1, and Dmytro S. Inosov2 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany. — 2Institut für Festkörperphysik, TU Dresden, Zellescher Weg 16, D-01069 Dresden, Germany. — 3Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex, France.
The geometrically frustrated trigonal cobaltate Ca3Co2O6 is considered to be a model system for a one-dimensional Ising-like antiferromagnet. Its crystal structure represents a hexagonal arrangement of one-dimensional chains, which consist of alternating nonmagnetic CoO6 octahedra and CoO6 trigonal prisms with a large magnetic moment.
Using inelastic neutron scattering, we have observed a quasi-one-dimensional dispersive magnetic excitation in the frustrated triangular-lattice spin-2 chain oxide Ca3Co2O6. At the lowest temperature (T= 1.5 K), this magnon is characterized by a large zone-center spin gap of ∼ 27 meV, which we attribute to the large single-ion anisotropy, and disperses along the chain direction with a bandwidth of ∼ 3.5 meV. In the directions orthogonal to the chains, no measurable dispersion was found. With increasing temperature, the magnon dispersion shifts towards lower energies, yet persists up to at least 150 K, indicating that the ferromagnetic intrachain correlations survive up to six times higher temperatures than the long-range interchain antiferromagnetic order.