Potential Skyrmion Host Fe(IO3)3: Connecting Stereo-active Lone-Pair Electron Effects to the Dzyaloshinskii-Moriya Interaction

TL;DR

This study demonstrates a new design strategy for skyrmion host materials by linking stereo-active lone-pair electrons and polar lattice symmetry, successfully synthesizing Fe(IO3)3 which exhibits a skyrmion phase driven by Dzyaloshinskii-Moriya interaction.

Contribution

The paper introduces a rational design approach connecting lone-pair electron effects to skyrmion stabilization, validated by synthesis and experimental evidence in Fe(IO3)3.

Findings

Fe(IO3)3 crystallizes in a polar chiral hexagonal lattice.

Evidence of skyrmion phase at 14-16 K and 2.5-3.2 T.

Short magnetic modulation wavelength of approximately 18 nm.

Abstract

Magnetic skyrmions, which are topologically distinct magnetic spin textures, are gaining increased attention for their unique physical properties and potential applications in spintronic devices. Here we present a design strategy for skyrmion host candidates based on combinations of magnetic spin, asymmetric building units having stereo-active lone-pair electrons, and polar lattice symmetry. To demonstrate the viability of the proposed rational design principles, we successfully synthesized Fe(IO3)3 polycrystalline sample and single crystals by using a new simplified low-temperature pathway, which is experimentally feasible for extending materials growth of transition metal iodates. Single crystal X-ray and powder synchrotron X-ray diffraction measurements demonstrated that Fe(IO3)3 crystallizes in the polar chiral hexagonal lattice with space group P63. The combined structural features of the macroscopic electric polarization along the c axis stemming from the coalignment of the stereo-active lone-pairs of the IO3 trigonal pyramid and the magnetic Fe3+cation residing on the three-fold rotation axis were selected to promote asymmetric exchange coupling. We find evidence of a predicted skyrmion phase at 14 K to 16 K and 2.5 T to 3.2 T driven by Dzyaloshinskii Moriya (DM) interaction, a conclusion supported by the appreciable DM exchange and the zero-field spiral antiferromagnetic ground state of Fe(IO3)3 deduced from neutron diffraction experiments. The associated magnetic modulation wavelength of the putative skyrmions is expected to be short, approximately 18 nm, comparable to the period of the DM-driven incommensurate order. This work links stereo-active lone-pair electron effects to enhanced DM interaction, demonstrating a new approach for chemical guidelines in the search for skyrmionic states of matter.