BiFeO₃epitaxial thin films and devices: past, present and future

Abstract

The celebrated renaissance of the multiferroics family over the past ten years has also been that of its most paradigmatic member, bismuth ferrite (BiFeO3). Known since the 1960s to be a high temperature antiferromagnet and since the 1970s to be ferroelectric, BiFeO3 only had its bulk ferroic properties clarified in the mid-2000s. It is however the fabrication of BiFeO3 thin films and their integration into epitaxial oxide heterostructures that have fully revealed its extraordinarily broad palette of functionalities. Here we review the first decade of research on BiFeO3 films, restricting ourselves to epitaxial structures. We discuss how thickness and epitaxial strain influence not only the unit cell parameters, but also the crystal structure, illustrated for instance by the discovery of the so-called T-like phase of BiFeO3. We then present its ferroelectric and piezoelectric properties and their evolution near morphotropic phase boundaries. Magnetic properties and their modification by thickness and strain effects, as well as optical parameters, are covered. Finally, we highlight various types of devices based on BiFeO3 in electronics, spintronics, and optics, and provide perspectives for the development of further multifunctional devices for information technology and energy harvesting.

Tetragonal BiFeO3 on yttria-stabilized zirconia

“…BFO is an ideal platform for manipulating the lattice, charge, orbital, and spin degrees of freedom via an electric field and therefore serves as a fertile playground for exploring new possibilities for next-generation electronics. [1][2][3][4][5][6][7][8] Recently, through an assistance of strain engineering in thin film process, BFO exhibits a rich variety of phases including rhombohedral, monoclinic, and orthorhombic structures. [9][10][11][12][13][14] Numerous efforts have also been made to reveal the fundamental understanding of correlation between structure and electric/magnetic order parameters.…”

Multiferroic Materials: Physics and Properties

“…119 BiFeO 3 (BFO) is one of the most studied thin film multiferroic single phase materials. 22,120 The bulk phase orders ferroelectrically at 1143 K and magnetically at 670 K as a G-type antiferromagnet with a superimposed incommensurate spin spiral that cancels out weak ferromagnetism due to spin canting, precluding linear magnetoelectric coupling. 121 The polarization was measured to be an order of magnitude higher than that observed in bulk until much later drastic improvements were made to the quality of bulk samples 24 and the measured polarization approached the same value.…”

“…With strain engineering a unique tetragonallike phase can be stabilised under highly compressive strain that does not exist in bulk. Under these strain conditions BFO shows an enhanced polarization and a higher piezoelectric response than lead zirconate titanate (PZT), 120 possibly providing a lead-free alternative to the conventionally used piezoelectric material PZT. Martin et al have published a detailed review on BFO and BiMnO 3 .…”

Interlayer strain effects on the structural behavior of BiFeO3/LaFeO3 superlattices

“…Indeed, coexistence of two robust ferroic properties (ferroelectricity with Tc= 830°C and antiferromagnetism with TN= 370°C) paves the way to applications in the field of information storage 1 . Important electromechanical properties were also detected in BFO thin films but are unfortunately limited by the high leakage currents.…”