Volume 85, Number 2, January 2009
Article Number 27010
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 30 January 2009
EPL, 85 (2009) 27010
DOI: 10.1209/0295-5075/85/27010

Torque anomalies at magnetization plateaux in quantum magnets with Dzyaloshinskii-Moriya interactions

S. R. Manmana and F. Mila

Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne - CH-1015 Lausanne, Switzerland

received 29 October 2008; accepted in final form 5 January 2009; published January 2009
published online 30 January 2009

We investigate the effect of Dzyaloshinskii-Moriya (DM) interactions on torque measurements of quantum magnets with magnetization plateaux in the context of a frustrated spin-1/2 ladder. Using extensive DMRG simulations, we show that the DM contribution to the torque is peaked at the critical fields, and that the total torque is non-monotonous if the DM interaction is large enough compared to the g-tensor anisotropy. More remarkably, if the DM vectors point in a principal direction of the g-tensor, torque measurements close to this direction will show well-defined peaks even for small DM interaction, leading to a very sensitive way to detect the critical fields. We propose to test this effect in the two-dimensional plateau system SrCu2(BO3)2.

75.10.Jm - Quantized spin models.
75.10.Pq - Spin chain models.
75.30.Gw - Magnetic anisotropy.

© EPLA 2009