Memory and Communication-in-Logic Using Vortex and Precessional Oscillations in a Magnetic Tunnel Junction

Abstract

Wearable and implantable devices (WIDs) come with several separate blocks such as pre-processing units, memory, and data transmission blocks. On the other hand, the multi-functional nature of spintronics devices such as memory, in-memory-computing, microwave frequency generation, and so on are paving paths for further advancement. Hence, in this paper, we present the concept of memory and communication-in-logic (MCL) using a magnetic tunnel junction (MTJ). In addition to reducing footprint area, this method also saves time and power consumption required for data transfer between the in-memory-computing and the communication blocks. Here, MTJ is presented as a memory device as well as an oscillator for communication purposes. Vortex-based spin-torque nano oscillators (V-STNO) and precessional STNOs (P-STNO) generate microwave frequency range (a few hundred MHz to a few GHz) wherein the frequency readout technique using the spin-torque diode is implemented for memory read function. In this work, a 300 nm nanodisk V-STNO generates 296 MHz and 312 MHz frequency for two states of chirality (a characteristic of magnetic vortex), respectively. These different frequencies can be sensed for a bit ‘0’/ ‘1’ read out through which the data from WIDs can be transmitted in a more energy and area-efficient way. The output power emission is 3.22 and 1.76 μW for bit ‘1’ and ‘0’, respectively for V-STNO which is three orders of magnitude larger than that of P-STNO. Finally, we demonstrate that V-STNO can transmit data up to 10 m in the air medium which is much longer than P-STNO (0.24 m).