Spin-lattice coupling mediated multiferroicity in (ND4)2FeCl5D2O

Abstract

We report a neutron diffraction study of the multiferroic mechanism in (ND4)2FeCl5D2O, a molecular compound that exhibits magnetically induced ferroelectricity. This material exhibits two successive magnetic transitions on cooling: a long-range order transition to an incommensurate (IC) collinear sinusoidal spin state at TN=7.3 K, followed by a second transition to an IC cycloidal spin state at TFE=6.8 K, the later of which is accompanied by spontaneous ferroelectric polarization. The cycloid structure is strongly distorted by spin-lattice coupling as evidenced by the observations of both odd and even higher-order harmonics associated with the cycloid wave vector, and a weak commensurate phase that coexists with the IC phase. The appearance of the 2nd-order harmonic coincides with the onset of the electric polarization, thereby providing unambiguous evidence that the induced electric polarization is mediated by the spin-lattice interaction. Our results for this system, in which the orbital angular momentum is expected to be quenched, are remarkably similar to those of the prototypical TbMnO3, in which the magnetoelectric effect is attributed to spin-orbit coupling.

5 pages, 4 figures

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Cited by in corpus (8)

• Structural, electronic, and magnetic properties of nearly-ideal $J_{\mathrm{eff}}$ $=$ 1/2 iridium halides
• Magnetic-Field-Induced Change of Magneto-Electric Coupling in the in Molecular Multiferroic (ND4)2[FeCl5(D2O)]
• Magnetoelectric coupling in the mixed erythrosiderite [(NH${}_4$)${}_{1-x}$K${}_x$]${}_2$[FeCl${}_5$(H${}_2$O)]
• Magnetic Excitations of the Hybrid Multiferroic (ND4)2FeCl5D2O
• Phase transitions of the ferroelectric $({\mathrm{ND}}_4{)}_2{\mathrm{FeCl}}_5\cdot {\mathrm{D}}_2\mathrm{O}$ under a magnetic field
• Single-crystal investigations on the multiferroic material LiFe(WO${}_4$)${}_2$
• Multiferroic domain relaxation in (NH4)2[FeCl5(H2O)]
• Reentrance of spin-driven ferroelectricity through rotational tunneling of ammonium