Magnetic Excitations of the Hybrid Multiferroic (ND<sub>4</sub>)<sub>2</sub>[FeCl<sub>5</sub>(D<sub>2</sub>O)]
ORAL
Abstract
(ND4)2[FeCl5(D2O)] is a molecular magnet exhibiting direct coupling between magnetism and electric polarization. Here we report a comprehensive inelastic neutron scattering study of the magnetic excitations in the zero-field incommensurate cycloidal phase and the high-field quasi-collinear phase. Accompanying with the field-induced magnetic phase transition, the spontaneous electric polarization direction changes from mostly aligned with the crystallographic a-axis to the c-axis, and the underlying multiferroic mechanism is believed to switch from the inverse Dzyalloshinskii-Moriya model to the p-d hybridization model. Our detailed data analysis using linear spin wave theory reveals that the spin dynamics of both multiferroic phases can be well-described by a Heisenberg Hamiltonian with an easy-plane anisotropy. However, the optimal model parameters show small but clear difference between the two phases, suggesting that delicate reorganizations of electronic degrees of freedom occurs in (ND4)2[FeCl5(D2O)] in response to external magnetic fields.
*Research conducted at ORNL's Spallation Neutron Source and High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U. S. Department of Energy.
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Presenters
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Wei Tian
- Oak Ridge National Laboratory, Oak Ridge
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Oak Ridge National Lab