Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 13: Spinstructures and magnetic Phase Transitions
MA 13.8: Vortrag
Dienstag, 27. März 2007, 12:00–12:15, H5
Uniform and Staggered Magnetizations Induced by Dzyaloshinskii-Moriya Interactions in Isolated and Coupled Spin 1/2 Dimers in a Magnetic Field — S. Miyahara1, J.-B. Fouet2, •S. Manmana3,4,5, R. Noack5, H. Mayaffre6, I. Sheikin7, C. Berthier6,7, and F. Mila3 — 1Dep. of Physics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558, Japan — 2IRRMA, PPH-Ecublens, CH-1015 Lausanne, Switzerland — 3Inst. of Theor. Phys., EPFL, CH-1015 Lausanne, Switzerland — 4ITP III, Univ. Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany — 5Fachb. Physik, Philipps-Univ., D-35032 Marburg, Germany — 6Lab. de Spectr. Phys., Univ. J. Fourier & UMR5588 CNRS, BP 87, 38402, Saint Martin d’Hères, France — 7GHMFL., CNRS, BP 166, F-38042 Grenoble Cedex 09, France
We investigate the interplay of Dzyaloshinskii-Moriya (DM) interactions and an external field in spin 1/2 dimers. For isolated dimers and at low field, we find in the limit where the D vector of the DM interaction is parallel to the external field a uniform magnetization perpendicular to the field. For larger fields, we find the staggered magnetization of an isolated dimer to have a maximum close to one-half the polarization. We investigate the effect of inter-dimer coupling in the context of ladders with Density Matrix Renormalization Group (DMRG) calculations and show that, as long as the parameters allow the staggered magnetization to be finite, the simple picture for isolated dimers is valid for weakly coupled dimers with minor modifications. The results are compared with torque measurements on Cu2(C5H12N2)2Cl4.