BLBK596-c01 BLBK596-Atulasimha Printer: Yet to Come December 22, 2015 14:44 Trim: 244mm × 170mm 1 Introduction to Spintronic and Nanomagnetic Computing Devices Jayasimha Atulasimha 1 and Supriyo Bandyopadhyay 2 1 Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA 2 Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA, USA This book focuses on recent developments in two important and interrelated information processing device concepts and related phenomena: “spintronic devices” and “nanomagnetic devices.” In the former, individual electron spins are coherently manipulated as they fow through the active region of a device to elicit device functionality. In the latter, an ensemble of spins in a nanostructure acts collectively as a giant classical spin (a single domain nanomagnet) owing to mutual exchange coupling, and the giant spin polarization (or the magnetization of the nanomagnet) is switched between stable orientations to store and/or process binary data. These information processing paradigms have attracted attention because of their low energy dissipation, nonvolatility and relatively fast speed of operation. 1.1 Spintronic Devices An iconic device in the feld of spintronics is the Datta-Das [1] Spin Field Effect Transistor (SPINFET) in which the current fowing between two of the terminals (source and drain) is modulated with a gate potential that does not change the carrier concentration in the channel of the transistor, but instead changes the spin polarization of the carriers. The source and drain contacts are ferromagnets that act as spin polarizers and analyzers. The source injects spin polarized electrons, the gate voltage precesses the spins in the channel owing to Rashba spin–orbit interaction [2] and the drain selectively transmits electrons depending on the degree Nanomagnetic and Spintronic Devices for Energy-Effcient Memory and Computing, First Edition. Edited by Jayasimha Atulasimha and Supriyo Bandyopadhyay. © 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd. 1 COPYRIGHTED MATERIAL