Integration of c-axis oriented Bi(3.15)Nd(0.85)Ti(2.95)Hf(0.05)O(12)/La(0.67)Sr(0.33)MnO(3) ferromagnetic-ferroelectric composite film on Si substrate

A La(0.67)Sr(0.33)MnO(3) (LSMO) ferromagnetic layer and a Nd(3+)/Hf(4+) co-substituted Bi(4)Ti(3)O(12) (Bi(3.15)Nd(0.85)Ti(3-x)Hf(x)O(12) (BNTH(x), x = 0, 0.025, 0.05, 0.1 and 0.15)) ferroelectric layer were successively deposited onto the (00 l)-oriented LaNiO(3) (LNO) layer buffered (001) Si substrate via all chemical solution deposition (CSD) method. As a result, the BNTH(x)/LSMO ferromagnetic-ferroelectric composite films integrated on Si substrate exhibit high c-axis orientation. The Nd(3+)/Hf(4+) co-substituted BNTH(x) films have the lower leakage current and the better ferroelectric properties than the mono-substituted Bi(4)Ti(3)O(12) (Bi(3.15)Nd(0.85)Ti(3)O(12) and Bi(4)Ti(2.95)Hf(0.05)O(12)) films. In particular, the BNTH(0.05)/LSMO/LNO film has the lowest leakage current density of 2.5 × 10(−7) A/cm(2) at 200 kV/cm, and the highest remnant polarization (Pr) of 27.3 μC/cm(2). The BNTH(0.05)/LSMO/LNO composite film also exhibits the soft ferromagnetism characteristics with a high saturated magnetization of 258 emu/cm(3) at 300 K, and the excellent magnetoelectric (ME) effect. The variations of ME voltage coefficient α (E) values with DC bias magnetic field H (bias) shows that the BNTH(0.05)/LSMO/LNO film has the high α (E) value at near zero H (bias). Moreover, at H (bias) = 0 Oe, the α (E) value gradually increases from zero with the increasing of the AC magnetic field frequency, and eventually reaches about 18.9 V/cm·Oe at 100 kHz, suggesting the existence of self-biased ME effect.