New family of materials for energy-efficient information storage and processing

This article briefly reviews a new family of multiferroic materials -- hexagonal rare earth ferrites -- that have been demonstrated ferroelectric and ferromagnetic simultaneously by experiments. Both the ferroeletricity and ferromagnetism in hexagonal ferrites originate indirectly from structural distortions, resulting in so-called improper ferroelectric and ferromagnetic orders. Naturally, structural distortions may mediate the coupling between the electric and magnetic polarizations in hexagonal rare earth ferrites, causing the MEM effect, as predicted by theory.

The possible MEM effect in rare earth hexagonal ferrites is particularly useful for information storage and processing because the non-volatile nature of the magnetic polarization avoids the energy cost of constant memory refreshing and a constant flow of current. The polarity of magnets are used to store information, for example, in the hard disk of computers. The information is modified by "writing" the polarity using a magnetic field, which requires a flow of current that costs significant amount of energy. If the polarity can be switched using an electric field (the MEM effect), the energy-efficiency will be greatly improved, because the generation of the electric field intrinsically needs less power than for generating a magnetic field. The fact that the electric field can be easily localized also suggests application in miniaturized devices.

This research was supported in part by Nebraska EPSCoR.