Nanoengineering room temperature ferroelectricity into orthorhombic SmMnO3 films

Abstract

Orthorhombic RMnO 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 RMnO 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~9 0 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 RMnO 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.

Role of oxygen vacancies in colossal polarization in SmFeO 3−δ thin films

“…2A, a remanent polarization P r [= (P r + −P r − )/2] of 4.14 C/cm 2 is achieved in this SmFeO 3− film at RT. This is two orders of magnitude higher than that of its bulk (19,29) and larger than that achieved in stoichiometric SFO epitaxial films in previous studies (30)(31)(32)(33), as well as the record of 1.95 C/cm 2 for the o-REMO 3 systems (34). This ferroelectricity was double-confirmed by the positive-up-negative-down (PUND) method, which is more accurate than the polarization-electric field (P-E) hysteresis loops because it can exclude the possible contribution from nonferroelectric artifacts.…”

High ionic conductivity in fluorite δ-bismuth oxide-based vertically aligned nanocomposite thin films

“…By extension, DMO epitaxially aligns with DSB with the same 45 relationship, as seen in other REMnO 3 phases. [21][22][23] This is also expected as DMO has the GdFeO 3 perovskite structure.…”

“…24 These observations are similar to previously reported (SmMnO 3 ) 0.5 ((-Bi,Sm) 2 O 3 ) 0.5 VAN lms. 21 In our lm, the DMO matrix plays an important role in stabilising the cubic DSB phase; the strained DMO and DSB have a $2% lattice mismatch. Thus, the strained DMO matrix acts as scaffold to stabilise and promote the formation of cubic DSB nanopillars.…”

Metal–Organic Precursor Synthesis, Structural Characterization, and Multiferroic Properties of GdFeO3 Nanoparticles

“… 41 In another recent study, in orthorhombic R MnO 3 ( R = rare-earth cation) perovskites, specifically SmMnO 3 that is reported have room-temperature ferroelectricity prepared by nano-engineering room temperature, ferroelectricity has been found due to a spin-driven mechanism. 42 , 43 We report the room-temperature ferroelectricity with a negligible leakage current in GdFeO 3 nanoparticles for the first time to the best our knowledge, which possess wide applications.…”