Study of physical properties of integrated ferroelectric/ferromagnetic heterostructures

Superlattices (SLs) with different periodicity of ferromagnetic La(0.7)Sr(0.3)MnO(3) (LSMO) and ferroelectric Ba(0.7)Sr(0.3)TiO(3) as constitutive layers were fabricated on conducting LaNiO(3) coated (001) oriented MgO substrates using pulsed laser deposition. The crystallinity, ferroelectric, and magnetic properties of the SLs were studied over a wide range of temperatures and frequencies. The structure exhibited ferromagnetic behavior at 300 K and ferroelectric behavior over a range of temperatures between 100 and 300 K. A frequency-dependent change in dielectric constant and tangent loss were observed above the ferromagnetic-paramagnetic temperature. The frequency-dependent dielectric anomalies are attributed to the change in metallic and magnetic nature of LSMO and also the interfacial effect of two different phases that are connected alternatively in series. The effect of ferromagnetic LSMO layers on ferroelectric properties of the SLs indicated strong influence of the interfaces. The asymmetric behavior of ferroelectric loop and the capacitance-voltage relationship suggest development of a built field in the SLs due to high strain across the interfaces. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3437627]