Dissertation/Thesis Abstract

Design Issues in Magnetic Field Coupled Array: Clock Structure, Fabrication Defects and Dipolar Coupling
by Kumari, Anita, Ph.D., University of South Florida, 2011, 117; 3449903
Abstract (Summary)

Even though silicon technology is dominant today, the physics (quantum electron tunneling effect), design (power dissipation, wire delays) and the manufacturing (lithography resolution) limitations of CMOS technology are pushed towards the scaling end. These issues motivated us towards a new paradigm that contributes to a continued advancement in terms of performance, density, and cost. The magnetic field coupled computing (MFC) paradigm, which is one of the regimes where we leverage and utilize the neighbor interaction of the nanomagnets to order the single-domain magnetic cells to perform computational tasks. The most important and attractive features of this technology are: 1) room temperature operation, which has been a limitation in electrostatic field coupled devices, 2) high density and nonetheless 3) low static power dissipation. It will be intriguing to address queries like, what are the challenges posed by the technology with such exotic features? Answer to such questions would become the focus of this doctoral research.

The fundamental problem with magnetic field coupled devices is the directional flow of information from input to output. In this work, we have proposed a novel spatially moving Landauer clock system for MFC nanomagnet array which has an advantage over existing adiabatic clock system. Extensive simulation studies were done to model and validate the clock for different length, size, and shape of nanomagnet array.

Another key challenge is the manufacturing defect, which leads to uncertainty and unreliability issues. We studied the different dominant types of geometric defects (missing material, missing cell, spacing, bulge, and merging) in array (used as interconnects) based on our fabrication experiments. We also studied effect of these defects on different segments (locations) of the array with spatially moving clock. The study concluded that a spatially moving clock scheme constitutes a robust MFC architecture as location of defect and length of arrays does not play any role in error masking as opposed to conventional clock.

Finally, the work presents the study on the 2D nanomagnet array for boolean logic computation and vision logic computation. The effect of dipole-dipole interaction on magnetization state transition in closely spaced 2D array of ferromagnetic circular nanomagnet was explored. The detailed design space to demarcate the boundary between single domain state and vortex state reveals that the single domain state space is desirable for Boolean logic computation while the space around the boundary would be appropriate for vision logic computing.

Indexing (document details)
Advisor: Bhanja, Sanjukta
Commitee: Alam, Syed M., Moreno, Wilfrido A., Sarkar, Sudeep, Wiley, Paris H.
School: University of South Florida
Department: Electrical Engineering
School Location: United States -- Florida
Source: DAI-B 72/06, Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Electrical engineering
Keywords: Clock system, Dipolar coupling, Fabrication defects, Micromagnetism, Nanomagnet array, Nanomagnetic logic, Reliability
Publication Number: 3449903
ISBN: 9781124576794
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