Varga, Tamas Droubay, Timothy C. Kovarik, Libor Nandasiri, Manjula I. Shutthanandan, Vaithiyalingam Hu, Dehong Kim, Bumsoo Jeon, Seokwoo Hong, Seungbum Li, Yulan Chambers, Scott A. Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO<sub>3</sub> Thin Films Polarization-induced weak ferromagnetism (WFM) was demonstrated a few years back in LiNbO<sub>3</sub>-type compounds, MTiO<sub>3</sub> (M = Fe, Mn, Ni). Although the coexistence of ferroelectric polarization and ferromagnetism has been demonstrated in this rare multiferroic family before, first in bulk FeTiO<sub>3</sub>, then in thin-film NiTiO<sub>3</sub>, the coupling of the two order parameters has not been confirmed. Here, we report the stabilization of polar, ferromagnetic NiTiO<sub>3</sub> by oxide epitaxy on a LiNbO<sub>3</sub> substrate utilizing tensile strain and demonstrate the theoretically predicted coupling between its polarization and ferromagnetism by X-ray magnetic circular dichroism under applied fields. The experimentally observed direction of ferroic ordering in the film is supported by simulations using the phase-field approach. Our work validates symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and WFM in MTiO<sub>3</sub> transition metal titanates crystallizing in the LiNbO<sub>3</sub> structure. It also demonstrates the applicability of epitaxial strain as a viable alternative to high-pressure crystal growth to stabilize metastable materials and a valuable tuning parameter to simultaneously control two ferroic order parameters to create a multiferroic. Multiferroic NiTiO<sub>3</sub> has potential applications in spintronics where ferroic switching is used, such as new four-stage memories and electromagnetic switches. MTiO 3 transition metal titanates;NiTiO 3;oxide epitaxy;phase-field approach;multiferroic family;crystal growth;WFM;ferromagnetism;metastable materials;four-stage memories;LiNbO 3;epitaxial strain;work validates symmetry-based criteria;ferroic order parameters;type compounds;thin-film NiTiO 3;coexistence;Multiferroic NiTiO 3;LiNbO 3 substrate;electromagnetic switches;LiNbO 3 structure;first-principles calculations;MTiO 3;polarization;order parameters;Films Polarization-induced;Lattice Polarization;bulk FeTiO 3 2017-06-09
    https://acs.figshare.com/articles/journal_contribution/Coupled_Lattice_Polarization_and_Ferromagnetism_in_Multiferroic_NiTiO_sub_3_sub_Thin_Films/5142148
10.1021/acsami.7b04481.s001