Nanoengineering room temperature ferroelectricity into orthorhombic SmMnO3 films

• Published in: Nature communications Vol. 11; no. 1; p. 2207
• Main Authors: Choi, Eun-Mi, Maity, Tuhin, Kursumovic, Ahmed, Lu, Ping, Bi, Zenxhing, Yu, Shukai, Park, Yoonsang, Zhu, Bonan, Wu, Rui, Gopalan, Venkatraman, Wang, Haiyan, MacManus-Driscoll, Judith L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 05.05.2020; Nature Publishing Group UK; Nature Portfolio
• Subjects: Antiferromagnetism; Broken symmetry; Compressive properties; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Condensed-matter physics; Coupling; Density functional theory; Electric devices; Electric polarization; Exchanging; Ferroelectric materials; Ferroelectricity; ferroelectrics and multiferroics; Ferromagnetism; Magnetic properties; Magnetism; materials science; Multiferroic materials; Nanocomposites; Nanoengineering; Rare earth elements; Room temperature; Tuning
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-16101-2

Abstract Orthorhombic R MnO 3 ( R  = rare-earth cation) compounds are type-II multiferroics induced by inversion-symmetry-breaking of spin order. They hold promise for magneto-electric devices. However, no spontaneous room-temperature ferroic property has been observed to date in orthorhombic R MnO 3 . Here, using 3D straining in nanocomposite films of (SmMnO 3 ) 0.5 ((Bi,Sm) 2 O 3 ) 0.5 , we demonstrate room temperature ferroelectricity and ferromagnetism with T C,FM  ~ 90 K, matching exactly with theoretical predictions for the induced strain levels. Large in-plane compressive and out-of-plane tensile strains (−3.6% and +4.9%, respectively) were induced by the stiff (Bi,Sm) 2 O 3 nanopillars embedded. The room temperature electric polarization is comparable to other spin-driven ferroelectric R MnO 3 films. Also, while bulk SmMnO 3 is antiferromagnetic, ferromagnetism was induced in the composite films. The Mn-O bond angles and lengths determined from density functional theory explain the origin of the ferroelectricity, i.e. modification of the exchange coupling. Our structural tuning method gives a route to designing multiferroics.