No abstract

In this study, we have fabricated (00l)-oriented Pb(Zr0.5Ti0.5)O3∕CoFe2O4∕Pb(Zr0.5Ti0.5)O3 (PZT/CFO/PZT) trilayer thin films on LaNiO3 coated substrates by dual-cathode rf sputtering system. The thicknesses of top and bottom PZT thin films were fixed at 100nm but those of the CFO interlayer were 40, 80, and 120nm, respectively. The x-ray diffraction showed well-defined PZT and CFO peaks with (00l) orientation, and large grains with columnar structure were observed by field-emission scanning electron microscopy. Hard-magnetic M-H loop with a saturation magnetization of ∼235emu∕cm3 and ferroelectric hysteresis curve with saturation polarization of ∼40.1μC∕cm2 were measured at room temperature for the PZT/CFO (120 nm)/PZT trilayer thin films. Due to the low-resistance CFO interlayer in series with the PZT layers, the ferroelectric property does not significantly vary with the CFO interlayer thickness. In contrast, the possibility of the existence of nonmagnetic interfacial layer at the CFO/PZT interface causes the reduction of the magnetization. Both of the good magnetic and ferroelectric responses suggest that the (00l)-oriented PZT/CFO/PZT trilayer thin film is a promising magnetoeletric material for study.

The strain effect on the magnetotransport properties in La0.9Sr0.1MnO3 films epitaxially deposited on SrTiO3 (STO) and LaAlO3 (LAO) substrates, is demonstrated. Large compressive strain is formed in the films on the LAO substrate; however, that on the STO is subject to a small tensile strain. Strain relaxation of films grown on both substrates results in the formation of a spin-canted antiferromagnetic (AFM) insulative phase, causing the increase in resistivity with decreasing temperature. The characteristics of the AFM insulative phase become apparent with increasing film thickness, which leads to a clear AFM transition in the films grown on LAO and a reduction of magnetization and Curie temperature in those on STO. The magnetoresistance effect of the films is also consistent with the above results.