  We present a study of the control of electric field induced strain on the
magnetic and electrical transport properties in a magneto-elastically coupled
artificial multiferroic Fe3O4/BaTiO3 heterostructure. In this Fe3O4/BaTiO3
heterostructure, the Fe3O4 thin film is epitaxially grown in the form of
bilateral domains, analogous to a-c stripe domains of the underlying
BaTiO3(001) substrate. By in-situ electric field dependent magnetization
measurements, we demonstrate the extrinsic control of the magnetic anisotropy
and the characteristic Verwey metal-insulator transition of the epitaxial Fe3O4
thin film in a wide temperature range between 20-300 K, via strain mediated
converse magnetoelectric coupling. In addition, we observe strain induced
modulations in the magnetic and electrical transport properties of the Fe3O4
thin film across the thermally driven intrinsic ferroelectric and structural
phase transitions of the BaTiO3 substrate. In-situ electric field dependent
Raman measurements reveal that the electric field does not significantly modify
the anti-phase boundary defects in the Fe3O4 thin film once it is
thermodynamically stable after deposition and that the modification of the
magnetic properties is mainly caused by strain induced lattice distortions and
magnetic anisotropy. These results provide a framework to realize electrical
control of the magnetization in a classical highly correlated transition metal
oxide.
