Physics and Applications of Bismuth Ferrite

Abstract

BiFeO3 is perhaps the only material that is both magnetic and a strong ferroelectric at room temperature. As a result, it has had an impact on the field of multiferroics that is comparable to that of yttrium barium copper oxide (YBCO) on superconductors, with hundreds of publications devoted to it in the past few years. In this Review, we try to summarize both the basic physics and unresolved aspects of BiFeO3 (which are still being discovered with several new phase transitions reported in the past few months) and device applications, which center on spintronics and memory devices that can be addressed both electrically and magnetically.

Control of ferroelectricity and magnetism in multi-ferroic BiFeO 3 by epitaxial strain

“…The coexistence of the polar and tilting structural instabilities yields a peculiar behaviour, completely different from that observed in classical ferroelectrics, such as PbTiO 3 or BaTiO 3 . Indeed, in BFO we find that the Curie temperature strongly decreases with strain, and that there is little change in the polarization.…”

“…Among multi-ferroics [1,2], BiFeO 3 (BFO) [3,4] has attracted a great deal of attention because of its high ferroic ordering temperatures (the Néel temperature T N is 640 K and the ferroelectric Curie temperature T C is 1100 K in the bulk) and large polarization (100 μC cm −2 in high-quality single crystals [5] and thin films [6]). BFO crystallizes in the R3c space group, with cations polarshifted along the pseudo-cubic 111 directions and FeO 6 octahedra rotated about the 111 axes.…”

Simple top-down preparation of magnetic Bi0.9Gd0.1Fe1−xTixO3nanoparticles by ultrasonication of multiferroic bulk material

“…Besides, in BiFeO 3 , magnetic ordering is of antiferromagnetic type, having a spiral modulated spin structure (SMSS) with an incommensurate long-wavelength period of 62 nm [12,14]. This spiral spin structure cancels the macroscopic magnetization and prevents the observation of the linear magnetoelectric effect [15][16][17]. These problems ultimately limit the use of bulk BiFeO 3 in functional applications.…”

Ferroelectric Field Effect Control of Magnetism in Multiferroic Heterostructures

“…This new class of artificially structured composite materials exhibits magnetoelectric couplings that are orders of magnitude larger that those typical of single-phase, intrinsic multiferroics Fiebig (2005); Ma et al (2011);Vaz et al (2010a). An example of the promise afforded by this approach is provided by the particular case of the multiferroic perovskite BiFeO 3 , characterized by magnetic and ferroelectric critical temperatures well above room temperature (T m c = 643 K and T e c = 1100 K, respectively) Catalan & Scott (2009). BiFeO 3 has generated much interest recently, following the first report of the growth of epitaxial thin films Wang et al (2003) and the demonstration of very large electric polarizations in high quality single crystalline films and in bulk crystals Lebeugle et al (2007); Shvartsman et al (2007); Wang et al (2003).…”

“…The magnetic state is modified further by a break in center of symmetry and the presence of a ferroelectric polarization, which gives rise to a local spin canting between the two spin sublattices (and to a weak magnetic moment) through the Dzyaloshinskii-Moriya interaction Dzialoshinshkii (1957);Moriya (1960). In addition, the coupling of the polarization to gradients of the magnetization leads to an inhomogeneous spin configuration characterized by an incommensurate rotation of the total local spin along a 101 pc direction (indexed to the pseudocubic perovskite structure) and lying in the {121} pc plane, defined by the cycloid propagation direction and the electric polarization (with easy axes along 111 pc ), with a period of about 62 nm (spin cycloid) Catalan & Scott (2009) ;Picozzi & Ederer (2009);Sosnowska et al (1982). This spin cycloid averages out the magnetic moment and leads to a vanishing linear magnetoelectric coupling and to a small effective magnetoelectric response; however, at the nanoscale, there is a strong coupling between the electric polarization and the magnetic spins, since they are constrained to point perpendicular to each other, indicating that a change in the orientation of the electric polarization will result in a change in the spin direction Cazayous et al (2008); Lebeugle et al (2008).…”