Magnetoelectric Random Access Memory-Based Circuit Design by Using Voltage-Controlled Magnetic Anisotropy in Magnetic Tunnel Junctions

Abstract

We introduce a magnetoelectric junction driven by voltage-controlled magnetic anisotropy (VCMA-MEJ) as a building block for a range of low-power memory application. We present and discuss specifically two applications, magnetoelectric random access memory (MeRAM) and ternary contentaddressable memory (TCAM). The MEJ differs from a magnetic tunnel junction (MTJ) in that electric field is used to induce switching in lieu of substantial current flow in MTJ. Electric-fieldcontrol of magnetism can dramatically enhance the performance of magnetic memory devices in terms of switching energy efficiency and switching speed. The development of such an energy-efficient and ultra-fast memory has a potential to change the paradigm of a hierarchical memory system in the conventional computer architecture. By combining speed, low power, and high density, electric-field-controlled magnetic memory combines features of multiple separate memory technologies used in today's memory hierarchy. The performance of a VCMA-MEJs based MeRAM, especially in the case of one access transistor associated with one MEJ (1T-1R) structure, is evaluated by comparing it with that of phase-change RAM (PCRAM), resistive RAM (ReRAM), and spin transfer torque RAM (STT-RAM). MeRAM can achieve ultra-fast switching (<1 ns), low switching energy (~1 fJ), and compact cell size of 4 with a diode access device, as well as nonvolatility. For another application, we propose the VCMA-MEJ based TCAM, which will be referred to as MeTCAM, consisting of 4T-2MEJs. Since MeTCAM fully exploits the low-power and highdensity features of the VCMA effect both in write and search operation modes, it obtains a fast searching speed (0.2 ns) with the smallest cell area ( ) compared to previous works.Keywords-non-volatile memory, voltage-controlled magnetic anisotropy (VCMA), magnetoelectric junction (MEJ), magnetic tunnel junction (MTJ), magnetoelectric random access memory (MeRAM), ternary content-addressable memory (TCAM)

Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications

“…In this section we discuss a new phenomenon emerging from the main topic of this review, namely, the possibility to modify the PMA at transition metal/oxide interfaces by applying an electric field. This phenomenon often called voltage control of magnetic anisotropy (VCMA) has attracted considerable interest from both scientists and engineers since it represents a viable alternative to energy-demanding magnetic field-and/or STT-controlled magnetization switching in spintronic devices and paves the way to the latter with ultralow-power consumption [see, for example, Wang, Lee, and Amiri (2015) and Lin et al (2016)].…”

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

“…This paper reviews recent progress in the research of the VCMA effect and the challenges that are faced in developing new types of MRAM controlled by voltage, called voltage-torque MRAM (also called Magnetoelectric (ME)-RAM) [34,35,36,37,38,39]. Section 2 presents an overview of the early experimental observations of the VCMA effect in all-solid state devices and the concept of voltage-induced dynamic switching, with a discussion of the technical challenges.…”

Energy-Efficient Memory Using Magneto-Electric Switching of Ferromagnets

“…Matching of all bits in a row turns all the p-MOS OFF and match goes low, indicating that a match is found. The write and read energy per bit was found to be 0.072 fJ and 15 fJ, respectively, indicating two orders of magnitude improvement in write energy and comparable read energy as compared to previous works as in [29].…”