Anisotropic strain, magnetic properties, and lattice dynamics in self-assembled multiferroic CoFe2O4-PbTiO3 nanostructures.

We investigate the anisotropic stress dependent magnetic and phonon behaviors in self-assembled CoFe₂O₄-PbTiO₃ (CFO-PTO) nanostructures deposited on SrRuO₃ buffered SrTiO₃ substrates of various thickness. The increased vertical compressed stress with increasing thickness enhances the vertical magnetic anisotropy of CFO while gradually reducing the vertical polarization of PTO. By applying the magnetic-field dependent Raman scattering, the CFO-A_1g and T_2g(1) phonon frequencies shift oppositely because of the magnetostriction. Moreover, the PTO-A₁ mode intensities anomalously enhance and the A₁ and E mode frequencies, respectively, increase and decrease, which prove the existence of the stress-mediated magnetoelectric (ME) effect. This study shows that the ME transmission process is dominated by interfacial stress, which is critical for enhancing the ME efficiency. [ABSTRACT FROM AUTHOR]