Magnetic-field induced competition of two multiferroic orders in a triangular-lattice helimagnet MnI2

TL;DR

This study investigates how magnetic fields influence the multiferroic orders in a triangular-lattice helimagnet MnI2, revealing field-induced domain rearrangements, order competition, and complex polarization behaviors.

Contribution

It demonstrates the magnetic-field induced competition and reorientation of multiferroic orders in MnI2, highlighting the role of magnetic field direction and magnitude in controlling multiferroic domain states.

Findings

Discontinuous 120-degree flop of P-vector with 60-degree H rotation.

Change in q-direction from q||<1-10> to q||<110> above 3 T.

Enhanced q-flexibility and smooth P-vector rotation near 3 T.

Abstract

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.