New multiferroics and magnetoelectric oxides and mechanisms

Multiferroics are important functional materials featuring strongly coupled order parameters that can be manipulated by external fields. Magnetoelectric multiferroics  are receiving enormous attention as they open the road to new forms of multifunctional devices. However, they challenge our fundamental understanding of magnetic and ferroelectric order because a strong magnetoelectric coupling is incompatible with traditional mechanisms of ferroelectricity. The recent discovery of a new class of materials (type-II multiferroics) in which the magnetic and electric properties are strongly coupled is attracting very much interest because of the possibility to manipulate magnetism and spins by electric fields and vice-versa, to magnetically control electric charges. Future applications in information technology require new multiferroic materials fulfilling all technological requirements. Along with its technological functionalities, multiferroics are also of great interest in fundamental research into strongly correlated oxides and quantum matter.

Aside from the important strategies to produce magnetoelectricity in complex artificial oxide heterostructures, the discovery of this new class of “single phase” magnetoelectric compounds is stimulating the exploration of a wide range of possible new materials and mechanisms, as well as their better understanding. These activities are encouraging new experimental and theoretical methods. We are particularly interested in the search of novel materials and single-phase compounds of two new types of coupled multiferroicity, based on: (i) Spin driven coupling, where magnetic interaction and magnetic ordering cause ferroelectric polar orders or abrupt electrical anomalies; and (ii) Charge driven coupling, where electronic, orbital or charge orders are responsible for the electric polarization.