Laurent C. Chapon

Spin structure and magnetic frustration in multiferroic RMn2O5 (R=Tb,Ho,Dy)

We have studied the crystal and magnetic structures of the magnetoelectric materials RMn2O5 (R=Tb,Ho,Dy) using neutron diffraction as a function of temperature. All three materials display incommensurate antiferromagnetic ordering below 40 K, becoming commensurate on further cooling. For R=Tb,Ho, a commensurate-incommensurate transition takes place at low temperatures. The commensurate magnetic structures have been solved and are discussed in terms of competing exchange interactions. The spin configuration within the ab plane is essentially the same for each system, and the radius of R determines the sign of the magnetic exchange between adjacent planes. The inherent magnetic frustration in these materials is lifted by a small lattice distortion, primarily involving shifts of the Mn3+ cations and giving rise to a canted antiferroelectric phase.

Giant improper ferroelectricity in the ferroaxial magnet CaMn7O12.

In rhombohedral

Ferroelectricity Induced by Acentric Spin-Density Waves in YMn2O5

{\mathrm{CaMn}}_{7}{\mathrm{O}}_{12}

Competing magnetic interactions in the extended Kagome system YBaCo{sub 4}O{sub 7}

, an improper ferroelectric polarization of magnitude

Enhanced ferroelectric polarization by induced Dy spin order in multiferroic DyMnO3.

2870\text{ }\text{ }\ensuremath{\mu}\mathrm{C}\text{ }{\mathrm{m}}^{\ensuremath{-}2}

Wish: The New Powder and Single Crystal Magnetic Diffractometer on the Second Target Station

is induced by an incommensurate helical magnetic structure that evolves below

Nature of the magnetic order in Ca3Co2O6.

{T}_{\mathrm{N}1}=90\text{ }\text{ }\mathrm{K}

Scientific Reviews: GEM: The General Materials Diffractometer at ISIS-Multibank Capabilities for Studying Crystalline and Disordered Materials

. 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

Zigzag ladders with staggered magnetic chirality in the S=3/2 compound beta-CaCr2O4

{\mathrm{CaMn}}_{7}{\mathrm{O}}_{12}

Cu3Nb2O8: A Multiferroic with Chiral Coupling to the Crystal Structure

gives rise to the largest magnetically induced, electric polarization measured to date.