Strain-Induced Relaxor Multiferroicity at Room Temperature in Hexaferrite BaFe12O19 Thin Films
Abstract
Multiferroic materials that combine magnetic and electric order at room temperature are rare. Here, we demonstrate strain-induced room-temperature polar order in the ferrimagnetic hexaferrite BaFe12O19. First-principles calculations reveal a strain-tunable energy landscape with multiple competing dipolar configurations and predict that compressive strain favors polar distortions. Using an isostructural Sr1.03Ga10.81Mg0.58Zr0.58O19 substrate, we grow coherently strained BaFe12O19 films with 1.1% in-plane biaxial compression. Second-harmonic generation measurements demonstrate inversion-symmetry breaking and establish a strain-stabilized polar phase that persists to at least 1000 K. Multislice electron ptychography directly reveals enhanced off-centering of Fe3+ ions within the trigonal-bipyramidal sites of the strained films and spatially varying local polarization, demonstrating the formation of polar nanoregions. Path-integral Monte Carlo simulations further show that compressive strain suppresses quantum fluctuations and stabilizes these local polar distortions. Together, these results establish strain-engineered BaFe12O19 as a room-temperature relaxor multiferroic, in which robust ferrimagnetism coexists with nanoscale polar order. Our work demonstrates a route for transforming an incipient ferroelectric ferrimagnetic into a polar magnetic material through epitaxial strain.
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BibTeX
@misc{li2026straininduced,
title = {{Strain-Induced Relaxor Multiferroicity at Room Temperature in Hexaferrite BaFe12O19 Thin Films}},
author = {Yilin Evan Li and Harikrishnan KP and Sankalpa Hazra and Zhiren He and Jayanti Higgins and ChanJu You and Mario Brützam and Jiaqiang Yan and Anna Park and Maya Ramesh and Wenwen Zhao and Jayda Shine and David G. Mandrus and Ramamoorthy Ramesh and Ankit S. Disa and Christo Guguschev and Guru Khalsa and Craig J. Fennie and Venkatraman Gopalan and Yu-Tsun Shao and David A. Muller and Darrell G. Schlom},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21352},
eprint = {2609.21352},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21352},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Strain-Induced Relaxor Multiferroicity at Room Temperature in Hexaferrite BaFe12O19 Thin Films
AU - Yilin Evan Li
AU - Harikrishnan KP
AU - Sankalpa Hazra
AU - Zhiren He
AU - Jayanti Higgins
AU - ChanJu You
AU - Mario Brützam
AU - Jiaqiang Yan
AU - Anna Park
AU - Maya Ramesh
AU - Wenwen Zhao
AU - Jayda Shine
AU - David G. Mandrus
AU - Ramamoorthy Ramesh
AU - Ankit S. Disa
AU - Christo Guguschev
AU - Guru Khalsa
AU - Craig J. Fennie
AU - Venkatraman Gopalan
AU - Yu-Tsun Shao
AU - David A. Muller
AU - Darrell G. Schlom
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.21352
UR - https://arxiv.org/abs/2609.21352
AB - Multiferroic materials that combine magnetic and electric order at room temperature are rare. Here, we demonstrate strain-induced room-temperature polar order in the ferrimagnetic hexaferrite BaFe12O19. First-principles calculations reveal a strain-tunable energy landscape with multiple competing dipolar configurations and predict that compressive strain favors polar distortions. Using an isostructural Sr1.03Ga10.81Mg0.58Zr0.58O19 substrate, we grow coherently strained BaFe12O19 films with 1.1% in-plane biaxial compression. Second-harmonic generation measurements demonstrate inversion-symmetry breaking and establish a strain-stabilized polar phase that persists to at least 1000 K. Multislice electron ptychography directly reveals enhanced off-centering of Fe3+ ions within the trigonal-bipyramidal sites of the strained films and spatially varying local polarization, demonstrating the formation of polar nanoregions. Path-integral Monte Carlo simulations further show that compressive strain suppresses quantum fluctuations and stabilizes these local polar distortions. Together, these results establish strain-engineered BaFe12O19 as a room-temperature relaxor multiferroic, in which robust ferrimagnetism coexists with nanoscale polar order. Our work demonstrates a route for transforming an incipient ferroelectric ferrimagnetic into a polar magnetic material through epitaxial strain.
ER -