Javier F. Pulecio

Magnetic cellular automata coplanar cross wire systems

Quantum cellular automata has proposed an exclusive architecture where two coplanar perpendicular wires have the ability to intersect one another without signal degradation. The physical realization of cross wire architectures has yet to be implemented and researchers share concerns over the reliability of such a system. Here we have designed a coplanar cross wire layout for magnetic cellular automata (MCA) and have fabricated two different systems. The first system was implemented via two ferromagnetic coupled coplanar crossing wires and demonstrated all possible logic combinations. The second more complex cross wire system consisted of nine junctions and one hundred and twenty single domain nanomagnets. The complex system’s ability to reach an energy minimum combined with the demonstration of all combinations of the smaller system leads us to conclude that a cross wire system is physically feasible and reliable in MCA.

Magnetic Cellular Automata Wire Architectures

Magnetic cellular automata (MCA) is an unconventional approach to implement Boolean logic machines. Not only it has been able to prototypically demonstrate successful operation of logical gates at room temperature, but has also realized all the key components necessary to implement any Boolean function. This moves the viability of the technology ahead of other implementations of CA and solicits researchers to examine the various aspects of MCA. Here, we investigate a critical facet of the MCA system, the interconnecting wire. We present this research further reducing the size of the single-domain nanomagnet, approximately 100 × 50 × 30 nm3 and physically implement two types of MCA wire architectures: ferromagnetic and antiferromagnetic. We provided external magnetic fields to the systems and investigated the architectures ability to mitigate frustrations. By providing fields in the in-plane easy axis, in-plane hard axis, out of plane hard axis, and a spinning field, we have experimentally concluded that for conventional data propagation between logical networks, ferromagnetic wires provide extremely stable operation. The high order of coupling found under various directions of saturating magnetic fields demonstrates the flexible clocking nature of ferromagnetic wires and inches the technology closer to implementing complex circuitry.

Reliability of bi-stable single domain nano magnets for Cellular Automata

Quantum cellular automata, also known as QCA, has been touted as a pragmatic use of quantum phenomena which currently are detrimental in nano-transistor technology. Recently, QCA technologies has expanded into magnetism, an area referred to as magnetic QCA, by exploiting the magnetic coupling interaction between neighboring cells (nano-magnets). The interactions of orderly fabricated nano-magnets and the viability of nano-magnetic structures as logical building blocks has yet to be explored in great detail. We have fabricated nano-scale magnetic QCA cells and currently the scope entails determining how factors such as material, size, placement, and surface roughness affect the magnetic properties and coupling interactions between the nano- magnetic QCA cells.

Study of magnetization state transition in closely spaced nanomagnet two-dimensional array for computation

The present study investigated the dipole–dipole interaction for finite 2D arrays of ferromagnetic circular nanomagnets. Starting with two basic arrangements of coupled nanomagnets namely, longitudinal and transverse, different diameters, and thicknesses are studied. The phase plot results exhibit for longitudinal arrangements that the single domain state is pervasive over a large range of thickness values as compared to the transverse arrangement or isolated nanomagnet cases. The study is further extended to finite arrays (3 × 3 and 5 × 5) of circular nanomagnets. The magnetic force microscopy results show that arrays of nanomagnets favors antiferromagnetic ordering at remanence. We have correlated our experimental results with micromagnetic simulations. Based on our study, we can conclude that nanomagnets with 100 nm in diameter, 15 nm in thickness, and 20 nm in spacing have single domain states in an array configuration with one-step switching, which results in fast operation, a property ideal for comp...

Magnetic Cellular Automata wires

Magnetic Cellular Automata (MCA) is a novel take on an alternative technological actualization of Boolean logic machines. Not only has it been able to prototypically demonstrate successful operation of logical gates at room temperature; all key components necessary to implement any Boolean function has been realized. We present work further reducing the size of the single domain nano-magnet, approximately 100 × 50 × 30 nm, and physically implement two types of MCA wire architectures ferromagnetic and anti-ferromagnetic. We report the first physical implementation of shape engineered ferromagnetic wires and compare both wires under saturating magnetic fields in the Z direction. We have concluded experimentally, that for conventional data propagation between logical networks, ferromagnetic wires provide extremely stable operation. The high order of coupling we found under saturating magnetic fields demonstrates the flexible clocking nature of ferromagnetic wires and inches the technology closer to implementing complex circuitry.

Defect characterization in magnetic field coupled arrays

Magnetic Cellular Automata (MCA) utilizes mutual exchange energies of neighboring magnetic cells to order the single-domain magnetic cell which in turn performs computational tasks. In this paper, we study three dominant type of geometric defects (missing, spacing, merging) in array (used as interconnects) based on our fabrication experiments. We study effect of these defects in three segments of the array (near-input, center and near-output) and we have observed that location of these defects play an important role in masking of the errors. The observed simulation results indicate that most of the defects occurring around center and near-output would be masked generating correct behavior while defects in the near-input segment would mostly cause erroneous output. We also observe that MCA is extremely robust towards space irregularities, one of the most common form of defect we observed through our fabrication techniques.

Applications of Electron Beam Induced Deposition in nanofabrication

This paper presents applications in which electron beam induced deposition (EBID) is used to characterize, analyze, and fabricate, nanostructures and devices. High aspect ratio cylindrical ultra sharp (CUS) atomic force microscope (AFM) probe tips are grown on discarded AFM tips using EBID. AFM is done using these CUS probe tips and compared to standard commercially available AFM probes as a baseline. The use of EBID to deposit platinum nanodots on thin foils for use as a hard mask in the fabrication of quantum cellular automata cell structures is also reported. Successful EDS analysis was performed on these nanodots in a conventional scanning electron microscope (SEM) with a high spatial resolution normally found only in the scanning transmission electron microscope (STEM). These EDS results demonstrate the ability to capture pertinent material properties of nanostructures in a more manageable SEM, and therefore, forgo the necessary complexities associated with a standard STEM.

A review of magnetic cellular automata systems

In this work, we provide a literature review of magnetic cellular automata (MCA) systems. Magnetic Cellular Automata offers promise of low power and room temperature operations. Experimental proof-of-concepts of various logical components are already demonstrated and tested. In architecture, various forms of field induced clocking have been proposed. We direct the authors to most of the achievements and lead them to an few open problems.

Driving magnetic cells for information storage and propagation

Single domain magnets serve as an excellent mechanism to store and preserve Boolean information. This work is an effort to establish that information can not only be stored and altered as in memory but also can be propagated in a causal fashion from the driver to the driven cell in presence of an external clocking field.

An experimental demonstration of the viability of energy minimizing computing using nano-magnets

There has been recent proposals for the use of nano-magnets to directly solve quadratic minimization problems, especially those arising in computer vision applications. This is unlike proposals for using nano-magnets to represent binary states. A collection of nano-magnets, when driven to their ground states, can be seen to optimize a quadratic energy function that is determined by their relative placement. By controlling the relative placement of nano-magnets, we can change the energy function being minimized. In this work, we experimentally demonstrate this capability by fabricating and testing an example of a quadratic optimization problem that accomplishes line grouping.