Spin Wave Based Logic Circuits
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0998-J06-05
Spin Wave Based Logic Circuits Alexander Khitun1, Mingqiang Bao1, Joo-Young Lee1, Kang Wang1, Dok Won Lee2, and Shan Wang2 1 Electrical Engineering, University of California Los Angeles, 420 Westwood Plaza, Box 951594, Los Angeles, CA, 90095-1594 2 Stanford University, Stanford, CA, 94305-4045 ABSTRACT We investigate spin wave propagation and interference in conducting ferromagnetic nanostructures for potential application in spin wave based logic circuits. The novelty of this approach is that information transmission is accomplished without charge transfer. A bit of information is encoded into the phase of spin wave propagating in a nanometer thick ferromagnetic film. A set of “AND”, “NOR”, and “NOT” logic gates can be realized in one device structure by utilizing the effect of spin wave superposition. We present experimental data on spin wave transport in 100nm CoFe films at room temperature obtained by the propagation spin wave spectroscopy technique. Spin wave transport has been studied in the frequency range from 0.5 GHz to 6.0 GHz under different configurations of the external magnetic field. Both phase and amplitude of the spin wave signal are sensitive to the external magnetic field showing 60Deg/10G and 4dB/20G modulation rates, respectively. Potentially, spin wave based logic circuits may compete with traditional electron-based ones in terms of logic functionality and power consumption. The shortcomings of the spin wave based circuits are discussed. INTRODUCTION There is a growing interest in novel nanometer scale devices and architectures to address the shortcomings and drawbacks inherent to the traditional CMOS-based architecture as indicated in ITRS 2005. Spintronics is one of the most promising approaches in offering an alternative route to the traditional semiconductor electronics since spin signals as represented in magnetic properties may be read/written without the transfer of carriers (electrons). There is an impetus for the development of novel spinbased logic circuits that are aimed to provide high information/signal processing rates for lower dissipation/delay and scaleable to the nanometer range. Over the past few years, various types of nano-scale spin-based logic devices were proposed [1-4] to take advantage on the additional degree of freedom provided by spin. Since Datta and Das have proposed an electron wave modulator (usually referred to as Spin-Field Effect Transistor or Spin-FET) [1], there is a growing interest to potential spin-based devices as a potential alternative to metal-oxide semiconductor fieldeffect transistor (MOSFET). The original idea of Spin-FET is in the achieving of phase shift for spin polarized electron waves via the spin-orbit coupling in narrow-gap semiconductors. In general, the fundamental problem is in the feasibility of using quantum interference effects to enhance nanometer scale devices performance. We proposed to use spin waves as a mechanism for information transmission and processing
[5], and a first working spin-wave based logic circuit has
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