Review Bismuth centred magnetic perovskite: A projected multiferroic Asish K. Kundu a,n , Md. Motin Seikh b , Pranjal Nautiyal c a Discipline of Physics, Indian Institute of Information Technology, Design & Manufacturing, Dumna Airport Road, Jabalpur 482005, India b Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal 731235, India c Discipline of Mechanical Engineering, Indian Institute of Information Technology, Design & Manufacturing, Dumna Airport Road, Jabalpur 482005, India article info Article history: Received 22 May 2014 Received in revised form 14 November 2014 Accepted 14 November 2014 Available online 26 November 2014 Keywords: Perovskite Magnetic properties Multiferroics abstract In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO 3 and BiFeO 3 are the well-studied Bi-centred multi- ferroic oxides. BiMnO 3 is a ferromagnetic–ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO 3 phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of in- vestigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La 0.5 Bi 0.5 MnO 3 perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La 0.5 Bi 0.5 Mn 0.67 Co 0.33 O 3 with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s 2 lone pair of Bi 3 þ cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material. & 2014 Elsevier B.V. All rights reserved. 1. Introduction In the last few decades there has been an increasing interest in the understanding of the basic physics/chemistry of multiferroic and/or spintronic materials [1–13]. The interplay between the structural, magnetic and electronic properties gives rise to fasci- nating complex phenomena and therefore the basic physics of the materials is rich. More specifically, in the transition metal oxides strong interplay between lattice, charge, spin and/or orbital de- grees of freedom provides a fantastic playground to tune their physical properties. The control of magnetism by electric field is an important aspect for the development of low power spintronics. In this respect, the ferromagnetic-semiconductors/insulators are no- vel singular materials that could exhibit simultaneously electric and magnetic ordering [2,7–15]. They also have practical applica- tions in spintronic and magneto-dielectric based devices such as non-volatile memories, magnetic read heads, tunnel junction spin filtering etc. [1–10,16]. Also, the recent investigations on multi- ferroic and/or spin filtering in this type of thin films have en- hanced the possibility of device applications [16,17]. Various methods have been proposed to design single phase multiferroic/ spintronic or composite materials in which magnetism is con- trolled by electric field. Despite the numerous investigations on multiferroic/spintronic materials in the past few years a very few perovskites have been known to realize as ferromagnetic-in- sulators (FMI) [6–15,18–25]. Multifunctional materials (multiferroics, magneto-dielectric, spintronics etc.) have attracted increasing attention due to their possible applications towards storage materials and intriguing fundamental physics [1–10,16]. Among the naturally existing oxi- des, the presence of both ferromagnetism and ferroelectricity is a rare phenomenon, due to the incompatibility between magnetism and ferroelectricity [2]. This incongruity could be at the origin of a limited number of multiferroics, though the researchers are look- ing for such materials from more than six decades. This phe- nomenon often occurs in perovskite oxide having the general formula ABO 3 . In the process of exploration of a multiferroic perovskite, the following facts are now well established: (i) ferromagnetic (FM) and ferroelectric (FE) behaviours are mu- tually exclusive due to the d 0 electronic structure of the B-site element [2], (ii) the occupation of different B-site cations with varying ionic radius provide an opportunity to realize a polar ground state [12], and (iii) the lattice distortion induced by cations with lone pair electrons such as Pb 2 þ or Bi 3 þ play a primordial role on the FE properties as reported for PbTiO 3 in comparison with BaTiO 3 [8]. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jmmm Journal of Magnetism and Magnetic Materials http://dx.doi.org/10.1016/j.jmmm.2014.11.044 0304-8853/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. Fax: þ91 761 2632524. E-mail addresses: asish.k@gmail.com, asish.kundu@iiitdmj.ac.in (A.K. Kundu). Journal of Magnetism and Magnetic Materials 378 (2015) 506–528