Effect of the CoFe_(2)O_(4) thin film thickness on multiferroic property of (00l)-oriented Pb(Zr_(0.5)Ti_(0.5))O_(3)/CoFe_(2)O_(4)/Pb(Zr_(0.5)Ti_(0.5))O_(3) trilayer structure

摘要

In this study, we have fabricated (00l)-oriented Pb(Zr_(0.5)Ti_(0.5))O_(3)/CoFe_(2)O_(4)/Pb(Zr_(0.5)Ti_(0.5))O_(3) (PZT/CFO/PZT) trilayer thin films on LaNiO_(3) coated substrates by dual-cathode rf sputtering system. The thicknesses of top and bottom PZT thin films were fixed at 100 nm but those of the CFO interlayer were 40, 80, and 120 nm, 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 approx235 emu/cm~(3) and ferroelectric hysteresis curve with saturation polarization of approx40.1 (mu)C/cm~(2) 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.