High-density magnetoresistive random access memory operating at ultralow voltage at room temperature

Abstract

The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch−2, ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns.

Film size-dependent voltage-modulated magnetism in multiferroic heterostructures

“…Note that a small DC bias magnetic field of 40 Oe is applied to ensure a deterministic and reversible switching back to the initial [010] direction that is preset by annealing the Ni film in a magnetic field. Such bias fields can be easily obtained by employing a pinning or synthetic antiferromagnetic layer [91] in terms of the practical design of voltage-controlled magnetoresistive random access memory (MRAM) devices [59]. As shown in figure 6a, the maximum rotation angle (derived from the direction cosine m x ) at E = 0 slightly increases by 5 • as the thickness of the Ni decreases from 35 to 5 nm.…”

“…the length and width, assumed to be equal herein) of the magnetic film would also exert significant influence on the domain states as a result of the competing exchange and magnetostatic energy [79,80], for example, the film would display a uniform single-domain structure at small sizes owing to the dominative exchange anisotropy, whereas it would be in a multi-domain state at large sizes in order to reduce the magnetostatic energy. These domain structures would lead to different voltage-induced magnetizationswitching characteristics accordingly [57,58], which is critical to the potential device application [59,60]. Here, we use a phase-field model [81][82][83] to investigate such lateral size-dependent voltage manipulation of magnetization.…”

“…It is also worth noting that the required actuation electric field is ultralow (|E| < 0.2 V µm −1 ), and would thus lead to an ultralow write energy [59]. [59]. )…”

“…Nonetheless, 5 nm could be a well-compromised thickness for the metallic Ni layer grown on PMN-PT based on the results in figure 6. It is also worth noting that the required actuation electric field is ultralow (|E| < 0.2 V µm −1 ), and would thus lead to an ultralow write energy [59]. [59].…”

Phase diagrams of magnetic state transformations in multiferroic composites controlled by size, shape and interfacial coupling strain

“…Conventionally, the different orientations of the polar state are regarded as logic "0" and "1". 38 Recently, it has also been proposed to use the different configurations (counterclockwise or clockwise rotation of in-plane magnetization flux, and up or down direction of out-of-plane magnetization at the vortex core) of the 1-vortex state to represent different logic states. 39 Depending on the size and shape of the magnetic nanodot, the electric field can not only readily control the magnetization orientation, but also control the vortex number and the polar-vortex transformation.…”