Coupled Magnetic Cycloids in Multiferroic TbMnO3 and Eu3/4Y1/4MnO3

Abstract

Based on the detailed Mn L-2,L-3-edge x-ray resonant scattering results, we report a new complexity in the magnetic order of multiferroic orthomangnites, which has been considered as the simple A-type cycloid order inducing ferroelectricity. The Dzyaloshinskii-Moriya interaction involved in the orthorhombic distortion brings on F-type canting from the A type, and the ordering type becomes the off-phase synchronized bc cycloid in TbMnO3 or the tilted antiphase ab cycloid in Eu3/4Y1/4MnO3. The F-type canting is responsible for the magnetic field-driven multiferroicity to weak ferromagnetism transition.