Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 5: Niedrigdimensionale Systeme, Magnetotransport I
TT 5.8: Vortrag
Montag, 11. März 2002, 16:30–16:45, H20
Raman spectra of the 1D spin ladder compounds SrCu2O3 and CaCu2O3 — •A. Gößling1, U. Kuhlmann1, C. Thomsen1, A. Löffert2, C. Gross2, W. Assmus2, K. Ruck3, and G. Krabbes3 — 1Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin — 2J.W. Goethe-Universität, Physikalisches Institut - Kristallabor, Robert-Mayer-Str. 2-4, 60054 Frankfurt a. M. — 3Institut für Festkörper- und Werkstofforschung Dresden, Postfach, 01171 Dresden
Using micro Raman spectroscopy we investigated magnetic excitations in the one dimensional spin ladder systems SrCu2O3 and CaCu2O3 in dependence on temperature. In SrCu2O3 we observed in addition to phonons two peaks at about 1200 and 3100 cm−1. Their intensity decreased exponentially with temperature. We apply two models in an attempt to explain this behavior: first magnon-magnon scattering [1] and second a resonant electronic excitation followed by magnon-magnon scattering [2]. Whereas SrCu2O3 does not seem to have long range 3D order, CaCu2O3 has a Néel temperature of about 27 K derived by susceptibility measurements [3]. In comparison with SrCu2O3 the antiferromagnetic coupling along the rungs of the ladders in CaCu2O3 is reduced by an out of plane Cu-O-Cu arrangement. We discuss the Raman spectra of both compounds.
[1] R. Citro et al., cond-mat/0012069.
[2] D. K. Morr et al., Phys. Rev. B 56, 9134 (1997).
[3] K. Ruck et al., Mater. Res. Bull. 36, 1995 (2001).