Computing with spins and magnets

Abstract

Abstract:The possible use of spin and magnets in place of charge and capacitors to store and process information is well known. Magnetic tunnel junctions are being widely investigated and developed for magnetic random access memories. These are two terminal devices that change their resistance based on switchable magnetization of magnetic materials. They utilize the interaction between electron spin and magnets to read information from the magnets and write onto them. Such advances in memory devices could also translate into a new class of logic devices that offer the advantage of nonvolatile and reconfigurable information processing over transistors. Logic devices having a transistor-like gain and directionality could be used to build integrated circuits without the need for transistor-based amplifiers and clocks at every stage. We review device characteristics and basic logic gates that compute with spins and magnets from the mesoscopic to the atomic scale, as well as materials, integration, and fabrication challenges and methods.

Radiation-hardened MRAM-based LUT for non-volatile FPGA soft error mitigation with multi-node upset tolerance

“…MTJs consist of two ferromagnetic layers, called fixed layer and free layer, which are separated by a thin oxide barrier layer such as MgO. Fixed layer is magnetically pinned and used as a reference layer, while the free layer magnetic orientation can be readily changed and is leveraged as a storage layer [30]. The tunnel magnetoresistance (TMR) effect incurs two distinct resistance levels for MTJ devices, which are defined by the angle between the magnetization orientations of the two ferromagnetic layers, as expressed by the following relations [31,32].…”

A building block for hardware belief networks

“…This is the quantity that determines the maximum fan-out that is possible which is particularly important if we want a high degree of inter connectivity. The physics of SHE 28 29 30 31 helps provide gain since for each device, it can be designed 23 32 33 to provide more spin current to the WRITE magnet than the charge current provided by the READ unit of the preceding stage.…”

“… Design for a transynapse: ( a ) Device structure: For our simulations we use the same design as that in Datta et al 23 which provides the required gain, fan-in and fan-out, making use of the established physics of the spin Hall effect (SHE) for the input and the magnetic tunnel junction (MTJ) for the output. (see also refs 32 , 33 ) However, instead of the deterministic mode described earlier, we operate it in a probabilistic mode as described next. ( b ) The WRITE and READ magnets are both initialized along their hard axis and allowed to relax in the presence of an exponentially decaying current (see inset) I IN ( t ) and decay time parameter τ dec .…”

Subthreshold Spintronic Stochastic Spiking Neural Networks With Probabilistic Hebbian Plasticity and Homeostasis

“…The field of spintronics aims to utilize the properties of nanoscaled magnetic structures to realize computational and nonvolatile memory elements [20]- [22]. The most well-developed spintronic device is the magnetic tunnel junction (MTJ) shown in Fig.…”