Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.72: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Raman Scattering from the S=1/2 Heisenberg Antiferromagnet on the Triangular Lattice — Natalia Perkins1,2 and •Wolfram Brenig3 — 1Physics Department, University of Wisconsin-Madison, Madison, WI 53706-1390, U.S.A. — 2Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia — 3Institute for Theoretical Physics, Technical University of Braunschweig, 38106 Braunschweig
Magnetic Raman scattering provides for an effective tool to investigate the spectrum of singlet excitations at small momenta in quantum magnets. In this context the two-magnon Raman spectrum (2M-RS) has been studies extensively in two- and three-dimensional collinear antiferromagnets. Here we present results from a calculation of the 2M-RS of the two-dimensional triangular S=1/2 antiferromagnet, which orders in a non-collinear 120∘-structure. First, and using spin-wave theory to O(1/S), we show that the bare 2M-RS has its maximum strongly shifted off from the upper bound of the two-magnon continuum. This is due to significant 1/S-corrections of the one-magnon dispersion and is in sharp contrast to the 2M-RS of the square-lattice AFM. Second, we study the impact of 2M interactions on the 2M-RS by solving the corresponding Bethe-Salpeter equation numerically to leading order in 1/S. Finally the dependence of the 2M-RS on the scattering geometry will be clarified.