The single-phase multiferroic oxides: from bulk to thin film

Abstract

Complex perovskite oxides exhibit a rich spectrum of properties, including magnetism, ferroelectricity, strongly correlated electron behaviour, superconductivity and magnetoresistance, which have been research areas of great interest among the scientific and technological community for decades. There exist very few materials which exhibit multiple functional properties; one such class of materials is called the multiferroics. Multiferroics are interesting because they exhibit simultaneously ferromagnetic and ferroelectric polarizations and a coupling between them. Due to the nontrivial lattice coupling between the magnetic and electronic domains (the magnetoelectric effect), the magnetic polarization can be switched by applying an electric field; likewise the ferroelectric polarization can be switched by applying a magnetic field. As a consequence, multiferroics offer rich physics and novel devices concepts, which have recently become of great interest to researchers. In this review article the recent experimental status, for both the bulk single phase and the thin film form, has been presented. Current studies on the ceramic compounds in the bulk form including Bi(Fe,Mn)O3, REMnO3 andthe series of REMn2O5 single crystals (RE = rare earth) are discussed in the first section and a detailed overview on multiferroic thin films grown artificially (multilayers and nanocomposites) is presented in the second section.

Intrinsic electrical properties of LuFe2O4

“…Regrettably the applied electric field of 0.2 kV/cm in the latter work is by far below the typical values of coercive fields for the ferroelectric materials [usually about tens of kV/cm (Ref. 21)]. Therefore, such electric field is too low to polarize the presumed ferroelectric sample, even more regarding that it is not a single domain sample.…”

Magneto-electric coupling in multiferroic La0.8Bi0.2Fe0.7Mn0.3O3 ceramic

“…Most well known examples of existing multiferroics are BiFeO 3 [7] and BiMnO 3 [8]. Where BiFeO 3 (T C ~ 850 °C, T N ~380 °C ) is a canted antiferromagnet, which gives rise to weak ferromagnetism and later one is metastable, requiring high pressure conditions for synthesis of bulk phases [8,9].…”

Ferromagnetism and magnetodielectric effect in insulating LaBiMn4∕3Co2∕3O6 thin films

“…are of interest owing to their potential device applications, such as non-volatile memories, magnetic read heads, tunnel junction spin filtering etc 1 7,8 and diluted magnetic semiconductors 9 ). In the metal oxide members containing bismuth, ferromagnetism originates from superexchange interactions between adjacent cations through the oxygen and ferroelectricity likely originates from the lone pair electrons of the Bi 3+ ion, which induce structural distortions.…”