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Updated: May 24, 2026

Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Giant improper ferroelectricity in the ferroaxial magnet CaMn7O12
R D Johnson1, L C Chapon, D D Khalyavin
1Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom. r.johnson1@physics.ox.ac.uk
Abstract:
In rhombohedral CaMn7O12, an improper ferroelectric polarization of magnitude 2870 μC m(-2) is induced by an incommensurate helical magnetic structure that evolves below T(N1)=90 K. The electric polarization was found to be constrained to the high symmetry threefold rotation axis of the crystal structure, perpendicular to the in-plane rotation of the magnetic moments. The multiferroicity is explained by the ferroaxial coupling mechanism, which in CaMn7O12 gives rise to the largest magnetically induced, electric polarization measured to date.
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