Interplay of magnetic properties and doping in epitaxial films of h-REFeO3 multiferroic oxides

Multiferroic materials demonstrating coexistence of magnetic and ferroelectric orders are promising candidates for magnetoelectric devices. While understanding the underlying mechanism of interplaying of ferroic properties is important, tailoring their properties to make them potential candidates for magnetoelectric devices is challenging. Here, the antiferromagnetic Neel ordering temperature above 200 K is realized in successfully stabilized epitaxial films of (Lu,Sc)FeO3 multiferroic oxide. The first-principles calculations show the shrinkage of in-plane lattice constants of the unit cells of the films on different substrates which corroborates well the enhancement of the Neel ordering temperature (TN). The profound effect of lattice strain/stress at the interface due to differences of in-plane lattice constants on out of plane magnetic properties and on spin reorientation temperature in the antiferromagnetic region is further elucidated in the epitaxial films with and without buffer layer of Mn-doped LuFeO3. Writing and reading ferroelectric domains reveal the ferroelectric response of the films at room temperature. Detailed electron microscopy shows the presence of lattice defects in atomic scale. First-principles calculations show that orbital rehybridization of rare-earth ions and oxygen is one of the main driving force of ferroelectricity along c-axis in thin films of hexagonal ferrites.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement. A.B. acknowledges FCT fellowship SFRH/BPD/115625/2016. The authors acknowledge the access to electron microscopy facilities of the ScopeM, ETH. A.B. appreciates the Inorganic Materials Science group, MESA+ Institute, University of Twente, Netherlands for the use of PFM and XRD for some samples within ECIU mobility research grant