Vertically Aligned Nanocomposite BaTiO₃:YMnO₃ Thin Films with Room Temperature Multiferroic Properties toward Nanoscale Memory Devices

Self-assembled epitaxial BaTiO₃:YMnO₃ (BTO:YMO) vertically aligned nanocomposite thin films have been fabricated on SrTiO₃ (001) substrates using pulsed-laser deposition. A room temperature multiferroic response has been demonstrated in the thin films. Enormous strain has been generated in both phases (e.g., 1.4% compressive strain in BTO and 6.8% tensile strain in YMO out-of-plane) because of the large lattice mismatch. By tuning the deposition frequency, the microstructure and strain of the nanocomposite films are tailored, which leads to the property tuning in the nanocomposite films. It is found that strain plays an important role on the magnetic ordering of YMO and thus results in the room temperature ferromagnetic response. Combined with the ferroelectric response in the BTO:YMO nanocomposite thin films, a new room temperature multiferroic two-phase nanocomposite has been demonstrated. The room temperature magnetoelectric coupling has been demonstrated for this new system. Overall, the BTO:YMO thin film presents promising applications in sensors, data storage, and memory devices