Multiferroic Memory: A Disruptive Technology or Future Technology?

Abstract

The term "Multiferroic" is coined for a material possessing at least two ferroic orders in the same or composite phase (ferromagnetic, ferroelectric, ferroelastic); if the first two ferroic orders are linearly coupled together it is known as a magnetoelectric (ME) multiferroic. Two kinds of ME multiferroic memory devices are under extensive research based on the philosophy of "switching of polarization by magnetic fields and magnetization by electric fields." Successful switching of ferroic orders will provide an extra degree of freedom to create more logic states. The "switching of polarization by magnetic fields" is useful for magnetic field sensors and for memory elements if, for example, polarization switching is via a very small magnetic field from a coil underneath an integrated circuit. The electric control of magnetization is suitable for nondestructive low-power, high-density magnetically read and electrically written memory elements. If the system possesses additional features, such as propagating magnon (spin wave) excitations at room temperature, additional functional applications may be possible. Magnon-based logic (magnonic) systems have been initiated by various scientists, and prototype devices show potential for future complementary metal oxide semiconductor (CMOS) technology. Discovery of high polarization, magnetization, piezoelectric, spin waves (magnon), magneto-electric, photovoltaic, exchange bias coupling, etc. make bismuth ferrite, BiFeO3, one of the widely investigated materials in this decade. Basic multiferroic features of well known room temperature single phase BiFeO3in bulk and thin films have been discussed. Functional magnetoelectric (ME) properties of some lead-based solid solution perovskite multiferroics are presented and these systems also have a bright future. The prospects and the limitations of the ME-based random access memory (MERAM) are explained in the context of recent discoveries and state of the art research.

Palladium-based ferroelectrics and multiferroics: Theory and experiment

“…19,20,21,22,23 Due to the natural chemical incompatibility between magnetism and ferroelectricity in oxide perovskites, only a few single-phase multiferroic oxides exist with sufficiently large magnitude of polarization and magnetization for real device applications. Some of the well-known potential multiferroic materials are as follows: BiFeO3, YMnO3, Pb(Fe0.5Nb0.5)O3, Pb(Fe0.5Ta0.5)O3, Pb(Fe0.67W0.33)O3, TbMnO3, etc.…”

Effect of Co and Mg doping at Cu site on structural, magnetic and dielectric properties of α–Cu2V2O7

“…Moreover, a polarization flop occurs under the action of external magnetic field along a certain crystallographic direction. Later on, a number of such materials have been discovered which attracted great attention due to their potential applications for functional devices such as magnetic sensors, multiple state memory devices, spintronic devices, and so on [4][5][6].…”

Determination of rhombohedral structure of BiFeO3 single-domain-like films grown on SrTiO3 and LaAlO3 substrates by X-ray diffraction using $(2\bar{1}\bar{3})_{\text{hex}}$

“…[8][9][10][11] The use of the ME effect is attractive for the voltage control of magnetic random-access memory (V-MRAM) to reduce electric consumption during the writing process. 9,12,13) The rotation angles of O 6 octahedra related to Fe-O bond angles and lengths in rhombohedral BFO are crucial for the exchange bias. 14) These parameters are affected by the epitaxial strain from the substrates and the crystal symmetry of BFO; however, a detailed structural analysis has not been carried out.…”