Webinar – Magnetic Tunnel Junctions for Non-Conventional Computing

FREE Webinar Magnetic tunnel junctions (MTJs) represent the most useful devices coming out of spintronics research. Besides serving as the key components for magnetic field sensors and digital magnetic random access memories, magnetic tunnel junctions have recently been studied as building blocks for non-conventional computing, via utilizing their functions of non-linearity, stochasticity, etc. In this presentation we begin with the fundamental aspects of these devices and then share some of our research, as well as reliability-related issues found. In one of the early works, we demonstrated that by designing multi-domain MTJs, one can realize synaptic devices and activation function devices for convolutional neural network, where the synaptic weight and threshold function are realized by controlling the position of magnetic domain walls. Recently, we explore the possibility of building Hopfield neural network with MTJs by using their oscillatory or probabilistic switching properties. These computing hardwares, known as Boltzmann machine or Ising machine can be used to solve NP-hard combinatorial optimization problems more efficiently than traditional von Neumann architectures. Particularly, we look into the dynamical behavior of an electrically coupled array of gigahertz spin Hall nano-oscillators, a device where the magnetic layers of the forming MTJs undergo persistent precession. By developing a general analytical framework that describes injection locking of spin Hall oscillators with large precession angles, we show the mapping between the coupled oscillators’ properties and the Ising model. We then integrate the analytical model into a versatile Verilog-A device that can emulate the coupled dynamics of spin Hall oscillators in circuit simulators. This abstract model allows for the analysis of the performance of the spin Hall oscillator network at the circuit level using conventional electronic components and considering phase noise and scalability. The results provide design insights and analysis tools toward the realization of a CMOS-integrated spin Hall oscillator Ising machine operating with a high degree of time, space, and energy efficiency. Speaker(s): Luqiao Liu, Agenda: 11:00 AM Technical Presentation 11:45 AM Questions and Answers 12:00 PM Adjournment Virtual: https://events.vtools.ieee.org/m/322887