Multiferroic materials, which show simultaneous ferroelectric and magnetic ordering, exhibit unusual physical properties — and in turn promise new device applications — as a result of the coupling between their dual order parameters. We review recent progress in the growth, characterization and understanding of thin-film multiferroics. The availability of high-quality thin-film multiferroics makes it easier to tailor their properties through epitaxial strain, atomic-level engineering of chemistry and interfacial coupling, and is a prerequisite for their incorporation into practical devices. We discuss novel device paradigms based on magnetoelectric coupling, and outline the key scientific challenges in the field.

Multiferroics: progress and prospects in thin films.

Multiferroics, defined for those multifunctional materials in which two or more kinds of fundamental ferroicities coexist, have become one of the hottest topics of condensed matter physics and materials science in recent years. The coexistence of several order parameters in multiferroics brings out novel physical phenomena and offers possibilities for new device functions. The revival of research activities on multiferroics is evidenced by some novel discoveries and concepts, both experimentally and theoretically. In this review, we outline some of the progressive milestones in this stimulating field, especially for those single-phase multiferroics where magnetism and ferroelectricity coexist. First, we highlight the physical concepts of multiferroicity and the current challenges to integrate the magnetism and ferroelectricity into a single-phase system. Subsequently, we summarize various strategies used to combine the two types of order. Special attention is paid to three novel mechanisms for multiferroicity generation: (1) the ferroelectricity induced by the spin orders such as spiral and E-phase antiferromagnetic spin orders, which break the spatial inversion symmetry; (2) the ferroelectricity originating from the charge-ordered states; and (3) the ferrotoroidic system. Then, we address the elementary excitations such as electromagnons, and the application potentials of multiferroics. Finally, open questions and future research opportunities are proposed.

Multiferroicity: the coupling between magnetic and polarization orders

A2B′B″O6 perovskites: A review

The existence of a magnetodielectric (magnetocapacitance) effect is often used as a test for multiferroic behavior in new material systems. However, strong magnetodielectric effects can also be achieved through a combination of magnetoresistance and the Maxwell-Wagner effect, unrelated to true magnetoelectric coupling. The fact that this resistive magnetocapacitance does not require multiferroic materials may be advantageous for practical applications. Conversely, however, it also implies that magnetocapacitance per se is not sufficient to establish that a material is multiferroic.

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Magnetocapacitance without magnetoelectric coupling

Interfaces between insulating oxides have revealed exotic electronic and magnetic properties. It is now shown that a complex magnetic structure can emerge in an oxide superlattice, and that specific interfaces can unexpectedly exhibit exchange bias. The observations reveal the induction of antiferromagnetism in a material that is usually paramagnetic.

Exchange bias in LaNiO3-LaMnO3 superlattices.

Magnetocapacitance and Magnetoresistance Near Room Temperature in a Ferromagnetic Semiconductor: La2NiMnO6

Giant room-temperature magnetodielectric response in the electronic ferroelectric LuFe2O4

Magnetocapacitance and Magnetoresistance Near Room Temperature in a Ferromagnetic Semiconductor: La2NiMnO6.

Water absorption resistant compositions of the present disclosure, e.g., pastes (or solutions), are well suited for electronic screen-printable materials and electronic components. The composition of the present disclosure may optionally contain thermal crosslinking agents, adhesion promoters, and other inorganic fillers. The composition of the present disclosure can have a glass transition temperature greater than 250° C. and a water absorption factor of less than 2%, and a positive solubility measurement.

Compositions comprising polyimide and hydrophobic epoxy and phenolic resins, and methods relating thereto

We have performed high-index immersion fluid studies to define the levels of both soluble and insoluble impurities
present. These studies have also revealed the importance of process materials' purity in fluid contact. Fluid interactions
with resist, leading to both surface and imaging defects, can be minimized by proper resist selection. Our Active Recycle
Package technology can greatly extend the useful life of both the fluid itself, as well as the final lens element.

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Nyrissa S. Rogado

Papers

Magnetocapacitance and Magnetoresistance Near Room Temperature in a Ferromagnetic Semiconductor: La2NiMnO6

Giant room-temperature magnetodielectric response in the electronic ferroelectric LuFe2O4

Magnetocapacitance and Magnetoresistance Near Room Temperature in a Ferromagnetic Semiconductor: La2NiMnO6.

Compositions comprising polyimide and hydrophobic epoxy and phenolic resins, and methods relating thereto

High-index immersion fluids enabling cost-effective single-exposure lithography for 32 nm half pitches