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

We introduce a magnetoelectric junction driven by voltage-controlled magnetic anisotropy (VCMA-MEJ) as a building block for a range of low-power memory applications. We present and discuss specifically two applications, magnetoelectric random access memory (MeRAM) and ternary content-addressable 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 field control 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 ultrafast 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 merges 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, resistive RAM, and spin transfer torque RAM. MeRAM can achieve ultrafast switching (<1 ns), low switching energy (∼1 fJ), and compact cell size of 6 F² with a shared source region, 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 high density 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 (44 F²) compared to previous works.