Effect of misfit strain on multiferroic and magnetoelectric properties of epitaxial La0.7Sr0.3MnO3/BaTiO3 bilayer

La0.7Sr0.3MnO3/BaTiO3 (LSMO/BTO) bilayer films were grown on (0 0 1) oriented SrTiO3 (STO), LaAlO3 (LAO) and (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 (LSAT) substrates by pulsed laser deposition. The bilayer deposited on the LSAT substrate presented the best ferromagnetic properties due to the smallest lattice mismatch between LSAT and LSMO. However, the best ferroelectric properties and strongest magnetoelectric (ME) effect existed in the bilayer on the STO substrate due to the minimal compressive strain in the BTO film. All these showed similar frequency-dependent ME behaviour from 0.1 to 100 kHz, and the largest value of ME voltage coefficient (αE) was obtained on the STO substrate. The values of αE were around 263 mV cm-1 Oe-1, 202 mV cm-1 Oe-1 and 169 mV cm-1 Oe-1 at 1 kHz on STO, LSAT and LAO substrates, respectively, which were at least one order of magnitude higher than previously reported values for similar composites and were ascribed mainly to the rather low dielectric constant of the BTO film. (paper)