Robust room‐temperature ferroelectricity and magnetoelectric coupling effect in epitaxial CaTiO3/SmFeO3 thin films

Abstract

AbstractSmFeO3 has received the increasing scientific attention as a promising room‐temperature single‐phase multiferroic material with great application potential in the next‐generation spintronic devices. However, the ferroelectricity of SmFeO3 has remained as a controversial issue. In the present work, high resistivity incipient ferroelectric CaTiO3 was introduced as a charge blocking layer on an SmFeO3 thin film to suppress the leakage current. CaTiO3/SmFeO3/Nb–SrTiO3 (1 0 0) thin films were prepared by a PLD (pulsed laser deposition) process, and the epitaxial growth of thin films was confirmed by XRD (X‐ray diffraction) and HRTEM (high resolution transmission electron microscope) images. The interface strain resulted in the polar non‐centrosymmetry in space group P42/mc for SmFeO3, and subsequently the room‐temperature ferroelectricity was achieved with a robust remanent polarization of about 4.9 μC/cm2. The 180° switchable domain structure was confirmed by PFM (piezoelectric force microscope). Meanwhile, strong magnetoelectric coupling with magnetoelectric coefficient (αME) of about 2.5 V/(cm Oe) was observed. The present work has revealed the structural origin of ferroelectricity in an SmFeO3 thin film and provided the great reference for its room temperature multiferroic applications.