Modification of Second Harmonic Generation Signals From Multiferroic Nanofibers Under Changing Magnetic Field

Multiferroic materials have recently attracted widespread attention as a novel class of materials due to their diverse multifunctional properties and applications. In particular, multi-phase structures are easier to synthesis and more common at room temperature in comparison to the single-phase materials. The hybrid structures investigated in this study are Janus nanofibers consisting of two hemi-cylinders of ferroelectric barium titanate (BTO) and ferrimagnetic cobalt ferrite (CFO). The mechanism involved in the magnetoelectric (ME) coupling between the two phases for this particular system is strain. In this study, we used the optical second harmonic generation (SHG) technique to monitor changes in the ferroelectricity of the BTO half while modifying the magnetization of the CFO half. The optical investigation was performed on an ensemble of pre-aligned nanofibers. In addition, the polarizations of the SHG signal were analyzed at different magnetic field orientations. We observed a clear signature of the SHG polarization rotation as the magnetic field direction was changed. This result suggests the existence of a measurable ME coupling between the two phases of this hybrid structure at room temperature which is essential for realizing devices with multiferroic applications.