E-field controlled phase transformation in bismuth ferrite thin films, and effect of laser energy density

Heterostructures of BiFeO3/Pb(Mg1/3Nb2/3)O3-30%PbTiO3 (BFO/PMN-30PT) were fabricated by pulsed laser deposition. Electric fields (E) were applied on the PMN-30PT substrates along the in-plane and out-of-plane directions, and the induced strain of BFO was measured as a function of E by X-ray diffraction. Reciprocal space maps along the (110) zone axis evidenced that a monoclinic MA phase was induced in both PMN-PT and BFO, where the dominate domain structures could be switched between biaxial directions under application of in-plane E. Studies were done for films prepared under different laser energy densities (LED), in order to optimize the in-plane strain of BFO. A relatively low LED of 1 J/cm2 produced a better BFO thin film with larger in-plane strain.