Single-crystal investigations on the multiferroic material LiFe(WO4)2

Single-crystal investigations on the multiferroic material LiFe(WO4)2

S. Biesenkamp, D. Gorkov, D. Brüning, A. Bertin, T. Fröhlich, X. Fabrèges, A. Gukasov ,M. Meven, P. Becker, L. Bohaty, T. Lorenz and M. Braden, Phys. Rev. B 103 (2021) 134412.

The crystal and magnetic structures of multiferroic LiFe(WO4)2 were investigated by temperature and magnetic-field-dependent specific heat, susceptibility, and neutron diffraction experiments on single crystals. Considering only the two nearest-neighbor magnetic interactions, the system forms a J1, J2 magnetic chain, but more extended interactions are sizable. Two different magnetic phases exhibiting long-range incommensurate order evolve at TN1 ≈ 22.2 K and TN2 ≈ 19 K. First, a spin-density wave develops with moments lying in the ac plane. In its multiferroic phase below TN2, LiFe(WO4)2 exhibits a spiral arrangement with an additional spin component along b. Therefore, the inverse Dzyaloshinskii-Moriya mechanism fully explains the multiferroic behavior in this material. A partially unbalanced multiferroic domain distribution was observed even in the absence of an applied electric field. For both phases only a slight temperature dependence of the incommensurability was observed, and there is no commensurate phase emerging at low temperature or at finite magnetic fields up to 6 T. LiFe(WO4)2 thus exhibits a simple phase diagram with the typical sequence of transitions for a type-II multiferroic material.

DOI : http://doi.org/10.1103/PhysRevB.103.134412

Crystal structure in LiFe(WO4 )2