Multiferroic behaviour and the magneto-dielectric effect in Bi₅FeTi₃O₁₅ thin films

Abstract

Thin films of Fe-containing the Aurivillius phase Bi5FeTi3O15 (BFTO) were successfully prepared by chemical solution deposition. The microstructure, ferroelectric behaviours, magnetic properties and the magneto-dielectric effect were investigated systematically at room temperature (RT). A definite hysteresis loop of the BFTO film was obtained with the remanent polarization (2P r) ∼ 43.3 µC cm−2 under an electric field of 300 kV cm−1. To exclude the contribution of the leakage current to polarization, we studied the frequency dependence of hysteresis loops in the BFTO thin film and made positive-up–negative-down measurements. These results indicated the intrinsic ferroelectricity in the present BFTO film and it was supported by the ε–V curve. Furthermore, a weak ferromagnetism with an in-plane saturated magnetization (M s) of ∼ 1.7 emu cm−3 was also observed in the BFTO film, which may have originated from the Fe2+–O–Fe3+ nanocluster and the F-centre exchange (FCE) mechanism. Therefore, the ferromagnetism could be considered as in nanoregions. More importantly, the magneto-dielectric effect was found with a magneto-dielectric coefficient of ∼−2.8% at a frequency of 100 kHz at RT. The probable origins of magnetic anisotropy and the magneto-dielectric effect were discussed. All these results demonstrated the RT multiferroic behaviour of the BFTO film.

Multiferroic and dielectric properties of Bi4LaTi3FeO15 ceramics

“…Hence, incorporation of magnetic species into BIT matrix is particularly interesting for forming room temperature multiferroics with high resistance. Bi 5 Ti 3 FeO 15 (BTF) material, prepared by inserting BiFeO 3 into BIT matrix, exhibited the coexistence of ferroelectricity, magnetism and the coupling between them at room temperature [18][19][20][21][22][23]. Meanwhile, enhanced ferromagnetism could be observed by half substitution of Fe 3 þ by Co 3 þ in BTF because of the ferromagnetic interaction between the adjacent Fe 3 þ and Co 3 þ ions [24][25][26].…”

Investigations on Fe doped Ba0.95Sr0.05TiO3 single phase magnetodielectric compounds

“…In the third approach the magnetic ions like Fe, Co, Ni, W, Mn etc. are substituted in ABO 3 type ferroelectric systems [12][13][14][15][16][17][18]. The literature referred between 1 and 14 above are a few examples of each category and not a comprehensive review.…”

Magnetic, dielectric, and magneto-dielectric properties of rare-earth-substituted Aurivillius phase Bi6Fe1.4Co0.6Ti3O18

“…A rather weak MD effect was observed in Aurivillius phase, e.g., 0.7% at T¼10K [Ref. 13] and 2.8% at RT in Bi 5 FeTi 3 O 15 thin film,14 and 0.39% in Bi 5 Fe 0.5 Co 0.5 Ti 3 O 15 thin film 15. Mao et al reported that the MD effect of Bi 5 Fe 0.5 Co 0.5 Ti 3 O 15 can be substantially enhanced by the introduction of La into Bi sites and a larger MD value of 8.1% at RT under 1T was achieved.…”