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.

We report on the magnetodielectric properties of well-ordered epitaxial La2CoMnO6 films. The temperature dependence of the dielectric constant is measured in the 10–105Hz frequency range under applied magnetic fields up to 50kOe. As temperature is lowered, the dielectric constant decreases in the ferromagnetic regime and approaches a plateau below 100K. A significant enhancement in the dielectric constant under applied magnetic field is observed only in the ferromagnetic phase regime culminating around the transition temperature, while it is absent in the paramagnetic phase regime. Using Arrott plots, we also demonstrate that these films exhibit a second-order phase transition at their Curie temperature. The observed magnetodielectric characteristics of the films are interpreted using the phenomenological theory.