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A Multiferroic Morphotropic Phase Boundary
Journal article   Open access   Peer reviewed

A Multiferroic Morphotropic Phase Boundary

Tae Yeon Kim, Shashank Ojha, Bridget R Denzer, Michael Xu, Ching-Che Lin, Jesse Schimpf, Jaegyu Kim, Liyan Wu, Ramamoorthy Ramesh, Ilya Grinberg, …
Advanced materials (Weinheim), pe74920
05 Sep 2026
DOI: https://doi.org/10.1002/adma.74920
PMID: 42700399
url
https://doi.org/10.1002/adma.74920View
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Abstract

magnetoelectric effect bismuth ferrite multiferroics phase boundary magnetocapacitance Ferroelectricity Materials Science
Bismuth ferrite (BiFeO ) thin films possess large ferroelectric polarization and antiferromagnetic order, yet their magnetoelectric coupling is limited by weak intrinsic magnetization. Here, a multiferroic morphotropic phase boundary (MPB) is demonstrated wherein the crystal structure, polarization, and magnetic order simultaneously evolve across a chemically induced phase boundary in strain-engineered (1-x)BiFeO -(x)BaTiO thin films. Between 0.1 < x < 0.2, the crystal structure evolves from a monoclinic phase to a newly stabilized tetragonal phase through an intermediate mixed-phase region. This structural transition is accompanied by concurrent changes in magnetic order, resulting in dramatically enhanced functional responses as compared with those of BiFeO . Specifically, films with x = 0.2 exhibit larger electromechanical strains (≈ 0.3%, about three-times larger than BiFeO ) and a significantly enhanced magnetoelectric-coupling coefficient (α ≈ 416 mV cm Oe , nearly 1000- and 19-times larger than bulk and thin-film BiFeO , respectively). These enhancements diminish beyond the MPB (x > 0.2) and arise from polarization rotation and evolving spin configurations driven by the near degeneracy of competing ferroic states at the multiferroic MPB. These results establish a rare multiferroic MPB where both the polar and magnetic order evolve simultaneously, providing a promising strategy for designing materials with strongly coupled ferroic order parameters.

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