Engineer Unveils new spin on Future of Transistors with Novel Design

All-carbon spin logic gate.  Magnetoresistive GNR unzipped from carbon nanotube and controlled by two parallel CNTs on an insulating material above a metallic gate. As all voltages are held constant, all currents are unidirectional. The magnitudes and relative directions of the input CNT control currents ICTRL determine the magnetic fields B and GNR edge magnetization, and thus the magnitude of the output current IGNR.

All-carbon, spintronic proposal could lead to smaller, better performing structures in electronics. An engineer with the Erik Jonsson School of Engineering and Computer Science at The University of Texas at Dallas has designed a novel computing system made solely from carbon that might one day replace the silicon transistors that power today’s electronic devices. “The concept brings together an assortment of existing nanoscale technologies and combines them in a new way,” said Dr. Joseph S. Friedman, assistant professor of electrical and computer engineering at UT Dalla.

The resulting all-carbon spin logic proposal is a computing system that Friedman believes could be made smaller than silicon transistors, with increased performance. Transistors behave like switches, turning current on and off. In addition to carrying a charge, electrons have spin, which relates to their magnetic properties. In recent years, engineers have been investigating ways to exploit the spin characteristics of electrons to create a new class of transistors and devices called “spintronics.”

Friedman’s all-carbon, spintronic switch functions as a logic gate that relies on a basic tenet of electromagnetics: As an electric current moves through a wire, it creates a magnetic field that wraps around the wire. In addition, a magnetic field near a graphene nanoribbon – affects the current flowing through the ribbon. In traditional, silicon-based computers, transistors cannot exploit this phenomenon. Instead, they are connected to one another by wires. The output from one transistor is connected by a wire to the input for the next transistor, and so on in a cascading fashion.

In Friedman’s spintronic circuit design, electrons moving through carbon nanotubes create a magnetic field that affects the flow of current in a nearby graphene nanoribbon, providing cascaded logic gates that are not physically connected. Because the communication between each of the graphene nanoribbons takes place via an electromagnetic wave, instead of the physical movement of electrons, Friedman expects that communication will be much faster, with the potential for terahertz clock speeds. In addition, these carbon materials can be made smaller than silicon-based transistors, which are nearing their size limit. Friedman said he is working toward a prototype of the all-carbon, cascaded spintronic computing system will continue in the interdisciplinary NanoSpinCompute research laboratory.
https://www.nature.com/articles/ncomms15635 http://www.utdallas.edu/news/2017/6/5-32589_Engineer-Unveils-New-Spin-on-Future-of-Transistors_story-wide.html?WT.mc_id=NewsHomePageCenterColumn