Abstract
At ambient pressure and below 5.5 K, olivine-type hosts a multiferroic (MF) phase where a multicomponent, i.e., multi- magnetic order generates spontaneous ferromagnetism and ferroelectricity (FE) along the c axis. Under high the FE disappears above 6 GPa, yet the evolution of the magnetic structure remained unclear based on available data. Here we report high- single crystal neutron diffraction experiments in the MF phase at K. We observe clearly that the incommensurate spiral component of the magnetic order responsible for FE varies little with up to 5.1 GPa. With support from high synchrotron x-ray diffraction measurements at room temperature , the -driven suppression of FE is proposed to occur as a consequence of a crystal structure transition away from the olivine structure. In addition, in the low neutron scattering experiments an emergent nonhydrostatic component, i.e., a uniaxial stress, leads to the selection of certain multi- domains. We use this observation to deduce a double- conical magnetic structure for the ambient ground state, this being a key ingredient for a model description of the MF phase.
3 More- Received 29 March 2016
- Revised 13 July 2016
DOI:https://doi.org/10.1103/PhysRevB.94.024439
©2016 American Physical Society