Emerging Multiferroic Memories

Abstract

Thus far in this book, we have focused on ferroelectric and magnetic spin torque transfer memories. In this chapter, we describe the recent discoveries in the emerging field of multiferroic-based memories. In the last decade, considerable attention has been focused on the search for and characterization of new multiferroic materials as scientists and researchers have been driven by the promise of exotic materials functionality (especially electric field control of ferromagnetism). In this chapter we develop a holistic picture of multiferroic materials, including details on the nature

Impact of Isovalent and Aliovalent Doping on Mechanical Properties of Mixed Phase BiFeO3

“…Therefore, this finding provides considerable insight into doping effects on local strain and elasticity of BFO, whose implications may be also correlated to intriguing phenomena reported earlier including giant electromechanical response and anisotropic phase boundary conductivity . Furthermore, control of doping and hence elastic properties in BFO can be further exploited to develop other correlated functionalities such as nonvolatile strain conductivity and enhanced coupling between ferroelastic and ferroelectric order for nanoelectronics. − …”

“…Of all of the investigated materials, La-doped BFO exhibits extreme softening behavior and low strain states, leading to its characteristic feature of mixed phase regions with micron-long stripes. Our results thus give an insight of the tuning nanomechanical properties in BFO to enhance correlated functional properties and point to promising avenues for multifunctional applications. ,, …”

“…Our results thus give an insight of the tuning nanomechanical properties in BFO to enhance correlated functional properties and point to promising avenues for multifunctional applications. 43,46,50…”

Ferroelectric and Magnetic Properties of Hexagonal ErFeO3 Epitaxial Films

“…Multiferroic materials, characterized by more ferroic orders coexisting in a single phase, have attracted attention in the past few decades due to their potential in memories, novel spintronic devices, and energy conversion. − However, single-phase multiferroic materials are still limited, mostly because the polarization in traditional ferroelectrics originates from the off-centered ions, which are stable with full/empty orbitals, whereas magnetic order is usually fulfilled by ordered electron spins with partially filled orbitals . To obtain ferroelectric polarization in magnetic materials, specific mechanisms such as a lone-pair electron, charge ordering, and geometric ferroelectricity are required. , For example, the ferroelectricity of BiFeO 3 originates from the lone-pair electron; the lone-pair 6s 2 electrons of Bi 3+ are distributed locally, leading to spatial asymmetry and spontaneous polarization. , Likewise, in LuFe 2 O 4 , the alternate stacking of aliovalent cations (Fe 2+ /Fe 3+ ) provides ferroelectric polarization, which is the so-called charge-order-driven ferroelectrics …”

Toward Ultimate Memory with Single-Molecule Multiferroics

“…With the relentless pursuit of high-performance electronic devices and the rapid advancement of technology, augmentation of the data storage capacity has emerged as a pivotal objective in the development of electronic devices. Substantial strides have been achieved in this domain over the past few decades. − For example, considering the fact that the ferroelectric (FE) and magnetic orderings can coexist or even be strongly coupled in multiferroics, multiferroic random access memories (MFRAMs) have been designed and fabricated to not only achieve nonvolatility but also offer the possibility of combining the advantages of FE and magnetic access memories, i.e., electric writing combined with magnetic reading. − In particular, during writing, applying an electric field is generally easier and less energy costly than applying a magnetic field, while magnetic reading is faster and nondestructive and has no wear-out mechanism as compared to electric reading in storage …”