Abstract
Structural, magnetic, ferroelectric and magneto-electric (ME) studies of bilayer thin films of BaTiO3 (BTO)-Ni0.5Zn0.5Fe2O4(NZFO) prepared using pulsed laser deposition on platinized silicon substrate are reported. Thickness of BTO layer(≈400 nm) is kept the same and the thickness of the NZFO layer is varied from 25–150 nm to study the effects. The prepared films are studied using grazing incidence x-ray diffraction (GIXRD), Raman spectroscopy, atomic force microscopy (AFM), magnetization and ferroelectric loop tracer measurements. From GIXRD, all the films are found to be polycrystalline in nature. Raman data confirms the ferroelectric (tetragonal) and cubic phases of BTO and NZFO, respectively in the bilayers. It is observed from the AFM data that the growth of NZFO layer is correlated with that of bottom BTO layer for thickness 75 nm resulting in stress on the BTO phase evidenced from shifting of Raman mode corresponding to BTO. Room temperature magnetic and ferroelectric properties are shown by recording the room temperature M-H and P-E loops. Further, PUND (positive up and negative down) measurements are carried out to capture the true ferroelectric polarization of the films. ME properties of the films was probed by recording P-E measurements and PUND in the presence of external magnetic field and it is observed that the ME coupling is maximum for the film with NZFO layer thickness of 75 nm. The observed results are explained in terms of stress mediated ME coupling.
Published Version
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