Influence of paramagnetic La2/3Sr1/3MnO3 layer on the multiferroic property of Bi0.8Ba0.2FeO3 film

Abstract

Multiferroics simultaneously exhibit several order parameters such as ferroelectricity and antiferromagnetism, representing an appealing class of multifunctional material. As the only multiferroics above room temperature, BiFeO3 (BFO) becomes an attractive choice for a wide variety of applications in the areas of sensors and spintronic devices. The coexistence of several order parameters brings about novel physical phenomena, for example, the magnetoelectric coupling effect. It allows the reversal of ferroelectric polarization by a magnetic field or the control of magnetic order parameter by an electric field. Heterostructure interface plays an important role in enhancing the ferroelectric and magnetic properties of multiferroic materials. Furthermore, the magnetoelectric coupling at the interface between the antiferromagnetism BFO and a ferromagnetic film has the close relation with achieving a functional multiferroic-ferromagnetic heterostructure. In order to determine the relationship between the multiferroic property and the interface experimentally, we prepare the Bi0.8Ba0.2FeO3(BBFO)/La2/3Sr1/3MnO3(LSMO) heterostructure on an SrTiO3(STO) substrate by pulsed laser deposition, and the structure characteristics and ferroelectric and magnetic properties are investigated. X-ray diffraction analysis shows that BBFO and LSMO films are epitaxially grown as single-phase. The further study by high-resolution transmission electron microscopy determines that the BBFO film has a tetragonal structure. The ferroelectric and magnetic measurements show that the magnetic and the ferroelectric properties are simultaneously improved, and the maximum values of the remnant polarization (2Pr) and the saturation magnetization of the heterostructure at room temperature are about 3.25 C/cm2 and 112 emu/cm3, respectively. The reasons for enhancing the ferroelectric and ferromagnetic properties of heterostructure are demonstrated by X-ray photoelectron spectrum that shows being unrelated to the valence states of Fe element. On the contrary, interface effect plays a major role. In addition, the magnetic resistivities and dielectric properties of BBFO/LSMO heterostructure are investigated at temperatures in a range of 50 K to 300 K, finding that magnetoresistance (MR) and magnetodielectric (MD) are respectively about -42.2% and 21.9% at 70 K with a magnetic field of 0.8 T, and the transition of magnetic phase takes place near 180 K. Furthermore, the temperature dependences of magnetodielectric and magnetoloss (ML) present opposite tendencies, suggesting that magnetodielectric is caused by Maxwell-Wagner effect and the magnetoresistance. Experimental results reveal that heterogeneous interface effect shows the exceptional advantages in enhancing multiferroic property and magnetoelectric coupling effect of complex heterostructure material. It is an effective way to speed up the application of multiferroic materials.

Enhanced magneto-electric effect in manganite tricolor superlattice with artificially broken symmetry

“…In order to understand the true nature of the ME effect, P-E hysteresis loops of a series of tricolor SLs with various (n, m) are measured. Figure 4 depicts the change trends of ∆E c and ∆P r of SLs with (n, m) = (3, 15), (5, 9), (7,6), and (15,3) as functions of the periodicity m. It is obvious that ∆E c and ∆P r strongly depend on m. This clearly suggests that interfaces play a key role in strong ME and MD effects. Owing to spin-polarized carriers in manganite SLs, the local magnetic moments of Mn 3+ and Mn 4+ ions tend to be parallel when an external magnetic field is applied, which leads to an orbital reconstruction.…”

“…As shown in Fig. 3(a), the changes in the dielectric constant and loss for an SL with (n, m) = (3,15) are recorded in a frequency range of 1 kHz-1000 kHz at T = 30 K under external magnetic fields of 0 kOe, 5 kOe, and 10 kOe. Two important features can be seen.…”

“…Since the magneto-electric (ME) effect-induction of magnetization by an external electric field or induction of electric polarization by an external magnetic field-was theoretically confirmed in 1959-1960 by Astrov, [1][2][3] it has been the hottest topic in the field of condensed matter physics for a long period. During the last half of the 20th century, ME effects have been observed in many single-phase materials and composites.…”

Low leakage current resistive memory based on Bi1.10 (Fe0.95Mn0.05) O3 films

“…In this paper, the characteristics of resistance switching of multiferroic barium ferrite (BiFeO 3 -BFO) thin films were studied, and some meaningful experimental results were obtained. Multiferroic barium ferrite is the only single-phase multiferroic material with ferroelectric and ferromagnetic phase transition temperatures far above room temperature [9][10][11]. The ferroelectric phase transition temperature (TC) is 850 °C.…”