Continuous strain-mediated perpendicular magnetic anisotropy in epitaxial (111) CoFe₂O₄ thin films grown on LiTaO₃ substrates

Perpendicular magnetic anisotropy (PMA) in magnetic thin films has attracted much attention due to its potential applications in spintronics devices. Here, we report the continuous strain-mediated PMA in epitaxial (111) CoFe2O4 (CFO) thin films grown on (0001) LiTaO3 substrates. A large variation in lattice strain ( similar to 0.9%) in a continuous way is realized in the CFO thin films by changing substrate temperature during deposition due to the difference in the thermal expansion coefficient between CFO and LiTaO3. As a result, the PMA of the (111) CFO thin films can be continuously mediated by the strain with uniaxial magnetic anisotropy energy in the range of 0.12-14.69x10(6) erg/cm( 3). Furthermore, the strain as well as the consequent PMA in the (111) CFO thin films can be maintained within the thickness of 25-205 nm, which is consistent with the scenario of the magnetoelastic effect. Our results reveal that the CFO/LiTaO(3 )system can be regarded as an ideal platform to realize robust PMA and its continuous strain tuning in the (111) CFO thin films by virtue of strain-induced magnetic anisotropy.