Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)
MA 40.84: Poster
Freitag, 27. März 2009, 11:00–14:00, P1A
Electron Spin Resonance in 2D triangular Cr-spin lattices — •Mamoun Hemmida, Hans-Albrecht Krug von Nidda, and Alois Loidl — Experimentalphysik V, Elektronische Korrelationen und Magnetismus, Universität Augsburg, 86135 Augsburg, Germany
The spin dynamics in some two-dimensional (2D) triangular Cr-antiferromagnetic lattices, i.e. the rock salt compounds HCrO2, LiCrO2, and NaCrO2 as well as the delafossite compounds CuCrO2 and AgCrO2, have been investigated by electron spin resonance (ESR). In these oxides, the divergence of the temperature dependent linewidth, on approaching the Néel temperature TN from above, is well described in terms of a Berezinskii-Kosterlitz-Thouless (BKT) scenario [1-3] due to magnetic vortex-antivortex pairing. Except for LiCrO2, where TKT is close to TN, the broad fluctuation regime TKT < T < TN suggests an intermediate 2D liquid antiferromagnetic state in analogy to the melting scenario of a 2D triangular lattice described by Nelson, Halperin, and Young in the framework of a modified Kosterlitz-Thouless model [4,5].
[1] V. L. Berezinskii, Sov. Phys. JETP 32, 493 (1971).
[2] J. M. Kosterlitz and D. J. Thouless, J. Phys. C 6, 1181 (1973).
[3] J. M. Kosterlitz, J. Phys. C 7, 1046 (1974).
[4] B. I. Halperin and D. R. Nelson, Phys. Rev. Lett. 41, 121 (1978).
[5] A. P. Young, Phys. Rev. B 19, 1855 (1979).