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The square-lattice spiral magnet Ba_2CuGe_2O_7 in an in-plane magnetic field

A. Zheludev·S. Maslov·G. Shirane·Y. Sasago·N. Koide·K. Uchinokura·D. A. Tennant·S. E. Nagler
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Abstract

The magnetic structure of Ba_2CuGe_2O_7 is investigated by neutron diffraction in magnetic fields applied along several directions in the $(a,b)$ plane of the crystal. In relatively weak fields, $H\lesssim 0.5$~T, the propagation vector of the spin-spiral rotates to form a finite angle with the field direction. This angle depends on the orientation of $H$ itself. The rotation of the propagation vector is accompanied by a re-orientation of the plane of spin rotation in the spiral. The observed behaviour is well described by a continuous-limit form of a free energy functional that includes exchange and Dzyaloshinskii-Moriya interactions, as well as the Zeeman energy and an empirical anisotropy term.

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A. Zheludev, S. Maslov, G. Shirane, Y. Sasago, N. Koide, K. Uchinokura, D. A. Tennant, S. E. Nagler. 1997-07-16. The square-lattice spiral magnet Ba_2CuGe_2O_7 in an in-plane magnetic field. https://doi.org/10.1103/physrevb.56.14006

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