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Overview
My research is concentrated on bridging the applied and fundamental science of device physics. This results in a very interdisciplinary and exciting career. In particular, I am interested in understanding the fundamental physics that occur in low dimensional materials such as dynamics of magnetism and electron transport. I would like to connect these phenomena over several different scales (atomic, mesoscopic, microscopic) in order to abstract those interactions into higher level functionality for technologies such as memories, logic, oscillators, etc. This typically entails a holistic scientific approach from fundamental analytical models, to experimentation, to functional generalization.
Select Research Topics
Unique physics in Low Dimensional Materials
By constraining materials to dimensions ranging below 100 nanometers down to a few atomic layers new physical phenomena are exhibited which are unique to our classical understanding. Quantum tunneling, single domain magnetism, ballistic electron transport, and surface effects in ultra-thin films are just some of the systems that I am currently investigating. Ultimately my aim is to understand the fundamental mechanism driving the effect and then extract the functionality for devices such as sensors and computational machines. In order to do so, I am creating new fabrication and characterization techniques in order to study the systems dynamics and properties using cutting edge experimental physics including additive manufacturing and nano-stenciling, time resolved pump-probe experiments, epitaxial growth, superlattices, synchrotron x-ray microscopy, and tranmission electron micropscopy.
Topology and High Frequency Dynamics
Under the right conditions, the collective arrangement of atomic magnetic dipole moments can arrange themselves into unique magnetic quasi-particles. Generally this occurs when a ferromagnetic element is constrained in a two dimensional nanoscopic system. I am interested in essential quasi-static and high frequency dynamics of these magnetic quasi-particles, such as a magnetic skyrmions and vortices, within its isolated potential landscape far from equilibrium as well as when two or more quasi-particles directly affect each other’s motion due to strong coupling interactions. By understanding these fundamental mechanisms we may be able advantageously utilize the phenomena in real technologies such as spin vortex oscillators and discrete nano-magnetic antennae.
Magnetic Cellular Automata
Un-patterned ferromagnetic thin films have been used in several different applications, most notably for non-volatile magnetic hard disks. By patterning discrete ferromagnetic nano-elements and arranging them into predefined configurations we can create Boolean machines to perform logic operations through magnetostatic force fields. Each element is enumerated by the direction of the single domain magnetization into a ‘0’ or ‘1’ bit. The fundamental switching speed is governed by direct exchange interactions of the dipole moments and the stability of a Boolean state is function of the shape anisotropy and material properties (crystalline anisotropy, exchange length, and magnetic saturation). Understanding how complex arrangements of analog/digital type magnetic elements find local energy minima from different initial and excited conditions through various fundamental interactions continues to be an exciting area of physics in similar systems such as magnetic spin-ice structures.
Error-Tolerant Parallel Computing via Single domain Nanomagnetic discs
While
most, if not all, major technologies use Boolean machines to perform logic
operations, computer vision applications like object recognition and tracking allow for solutions that are
error-tolerant. By creating ultra-thin Permalloy discs that are positioned at
exact locations corresponding to parallel and 90 degree edges for example, salient features of an image can be detected. Interestingly, since
neighboring discs are coupled through dipolar fields, the entire system
consisting of numerous discs can find a local energy minimum through
magnetostatic interactions. Traditional logic device perform similar tasks in a
serial manner where using a non-boolean magnetic computing paradigm finds a
solution in nanoseconds through massively parallel dipolar interactions.
