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 preprocessing units, memory, and data transmission blocks. Hence, in this letter, we present the concept of memory and communication-in-logic (MCL) using a magnetic tunnel junction (MTJ). Here, MTJ is presented as a memory device as well as an oscillator for communication purposes. Vortex-based spin-torque nanooscillators (V-STNO) and precessional STNOs (P-STNO) generate a 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 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).