For the time being, research in multiferroic materials is a big topic (see isi-web to monitor the production every year during the last years). The reason is that there are some candidates having ferromagnetism and ferroelectricity (they will be importan for providing 4 logical memory states in electronics, instead of the used now ,2, 1&0) as RMnO3 (R=Y, Tb,..), BiFeO3,.., but all of them have week points. For example the bismuth ferrite has low polarization. For these reason the search for new Multiferroic materials with high ordering temperatures, high electric and magnetic polarization is of fundamental and applied relevance.

Multiferroic field is an excellent area for research despite some problem exist as rightly pointed out by JB Sir.

Excellent results have been obtained with the use of mulitferoic as spin polarized barrier in MTJ, which is other dimension of application of multiferroic materials.

Once we bring temperature close to room temperture (Most multiferroic are ferri or g type anti-ferro) then it will bring unimaginable applications. Still they are some promising material apart from bismuth ferrite to have good coupling between magnetization and polarization (nature wont allow this because of so called d0 Vs d9 problem) It is believed we cannot break this barrier (similar to HTC superconductors) but we can come close to this by creating artificial disorders.

Another important thing is that if we experimentally successful in bringing two d block elements with negative energies (in fact it is so difficult) in the form of pervoskite structure, we are so close to break the nature barrier.

In any case it is most prospectful field to do research.

Please read the sentence "Once we bring Neel temperature close....." in the above answer

@ J B sir and S R sir. Thank you very much, for you sharing you knowledge and adding to our knowledge by your valuable and informative comments. @Sridharan Ravi: I am entrusting to have a deeper understanding of the topic "Once we bring Neel temperature close to RT" and "2 d block elements with negative energies in the form of pervoskite structure will bring us close to break the nature barrier" and so want to read about it in detail. Can you suggest me some article or book related to this.

Formation energies are some important in terms of stability.(if it gives positive or close to positive, it means the species will be more stable and negative means it will practically difficult to realize)

For example, bismuth ferrite, (ABO3), A-Bi and B-Fe. have positive formation energy but its value is so close to zero. This is the reason for volatile nature of bismuth in bismuth ferrite. If your species have negative formation energy, it is difficult to realize practically in easier way, since they become so unstable. But if you bring a species within the formation energy in negative (say AB in which the formation of AB has negative energy) they have high difference in spin states say one with +4 bohr and other -1 bohr. This will in turn facilitate magneto-electric coupling in your species.

You can refer Half metallic alloys and its application (Springer ed.) and other related books dealing with formation energies on magnetic materials.

In the case neel temperature, when it is close to room temperature, you have max magnetization at room temperature range, enabling to switch over various states of logical operation easily.(keep in mind that bismuth ferrite has 650 K and we showed bismuth based double pervoskite has neel temperature close to 500 K)

Hi, i m not expert in scientific language for great materials like high temperature superconductors and multiferroics. Simple thing in this world what we learn is great people are not useful to many people. Similarly great materials where rich in physics content are not used by most of people. But there is still there are few percent of reasearchers and scientists are dying to understand the theory behind two different qualties present in the material. My friend if u want come to few percent or towards the high percent where they will live life simply. Think two contradictory characters present in the system. With out materials how can i think great theories in condensed matter physics. Finally plenty of research is going on to understand the science and engineer the properties the multiferroics and superconductors.

" if u donot know about tommorrow what will happen then day is intersting and if u know how tomorrow is then its boring. Tommorrow is not known for multiferroics. Every day is interesting"

For people interested in fundamentals of condensed matter, MFs is a great field, every system is unique in its way! so many ways of coupling and never ending. For applications, ME coupling is already shown high in composites. But not many applications out there. How to exploit this to consumer goods is another way of getting enthusiastic about MFs.