Magnetic and dielectric properties with varying magnitude and direction of magnetic field H have been investigated for a triangular lattice helimagnet MnI2. The in-plane electric polarization P emerges in the proper screw magnetic ground state below 3.5 K, showing the rearrangement of six possible multiferroic domains as controlled by the in-plane H. With every 60-degree rotation of H around the [001]-axis, discontinuous 120-degree flop of P-vector is observed as a result of the flop of magnetic modulation vector q. With increasing the in-plane H above 3 T, however, the stable q-direction changes from q||<1-10> to q||<110>, leading to a change of P-flop patterns under rotating H. At the critical field region (~3 T), due to the phase competition and resultant enhanced q-flexibility, P-vector smoothly rotates clockwise twice while H-vector rotates counter-clockwise once.
@article{arxiv.1103.5294,
title = {Magnetic-field induced competition of two multiferroic orders in a triangular-lattice helimagnet MnI2},
author = {T. Kurumaji and S. Seki and S. Ishiwata and H. Murakawa and Y. Tokunaga and Y. Kaneko and Y. Tokura},
journal= {arXiv preprint arXiv:1103.5294},
year = {2015}
}
Comments
4 pages, 3 figures. Accepted in Physical Review Letters