NONVOLATILE SPINTRONICS: PERSPECTIVES ON INSTANT-ON NONVOLATILE NANOELECTRONIC SYSTEMS

Abstract

Instant-on nonvolatile electronics, which can be powered on/off instantaneously without the loss of information, represents a new and emerging paradigm in electronics. Nonvolatile circuits consisting of volatile CMOS, combined with nonvolatile nanoscale magnetic memory, can make electronics nonvolatile at the gate, circuit and system levels. When high speed magnetic memory is embedded in CMOS logic circuits, it may help resolve the two major challenges faced in continuing CMOS scaling: Power dissipation and variability of devices. We will give a brief overview of the current challenges of CMOS in terms of energy dissipation and variability. Then, we describe emerging nonvolatile memory (NVM) options, particularly those spintronic solutions such as magnetoresistive random access memory (MRAM) based on spin transfer torque (STT) and voltage-controlled magnetoelectric (ME) write mechanisms. We will then discuss the use of STT memory for embedded application, e.g., replacing volatile CMOS Static RAM (SRAM), followed by discussion of integration of CMOS reconfigurable circuits with STT-RAM. We will then present the scaling limits of the STT memory and discuss its critical performance parameters, particularly related to switching energy. To further reduce the switching energy, we present the concept of electric field control of magnetism, and discuss approaches to realize this new mechanism in realizing low switching energy, allowing for implementation of nonvolatility at the logic gate level, and eventually at the transistor level with a magnetoelectric gate (MeGate). For nonvolatile logic (NVL), we present and discuss as an example an approach using interference of spin waves, which will have NVL operations remembering the state of computation. Finally, we will discuss the potential impact and implications of this new paradigm on low energy dissipation instant-on nonvolatile systems.