Physics Research Projects 2023

 

Eva Carmona-Rogina

Advisor: Xuemei Cheng

Creating simulations to examine asymmetric expansion of bubble skyrmions

Throughout the upcoming 2023 summer research program, I plan to apply micromagnetic simulation software to study the formation and behavior of magnetic bubble skyrmions, under the direction of Dr. May Cheng. Bubble skyrmions are topologically protected spin textures that have a circular shape. Their importance in modern science applications involves harnessing their stability, where the application of current can drive their motion. This method can be used to develop high-speed spintronic devices with low energy consumption and high data storage capacity. Research into bubble skyrmions could lead to the development of further miniaturization of digital memory media and computer logic structures.

The ground state of magnetic structure results from energy minimization of the total energy system. This total energy is composed of the summation of the Zeeman (potential energy), DMI (asymmetry), Anisotropic (easy magnetization direction), Dipolar (long-range), and Heisenberg Exchange (short-range) energy terms. By varying the strength of the parameters of these interaction terms, we will be able to model the magnetism of bubble skyrmion formation, where mumax3 software will be employed to develop various simulations.

In this summer’s work, I will investigate the asymmetric expansion of bubble skyrmions driven by applied in-plane magnetic fields in [Co(0.5nm)/Gd(1nm)/Pt(1nm)]10 magnetic multilayers. The multilayer system will be modeled, using mumax3, with parameters determined from experimental measurements on [Co(0.5nm)/Gd(1nm)/Pt(1nm)]10 magnetic multilayers. These simulations along with experimental PEEM imaging will provide insight into the asymmetric expansion of bubble skyrmions in the multilayer film.

Yingxiao (Thea) Liao

Advisor: Xuemei Cheng

Fabricating Gold Microdisks for Biomedical Application

Nanomaterials, characterized by sizes of 100 nm or smaller in at least one dimension, exhibit unique properties in comparison to their bulk counterparts, making them valuable across diverse domains such as electronics, medicine, and energy. Two commonly used techniques for fabricating nanomaterials are photolithography and sputtering. Photolithography enables users to design patterns by passing UV light through a photomask to selectively expose a photosensitive polymer that is coated on top of the substrate. During development, the photosensitive polymer is selectively dissolved to expose the desired portions of the underlying substrate. Sputtering is a film deposition method where target atoms are ejected into the gas phase and subsequently deposited as a film onto the substrate.

In this summer’s research, I will use lithography and sputtering to fabricate gold microdisks with nanometer thickness suspended in solution for future biomedical applications. The dimensions of the gold microdisks will be measured through small angle x-ray reflectivity and atomic force microscopy to confirm that they are as designed. The fabricated gold microdisks will be used in future experiments to shed light on the role target geometry plays in phagocytosis.

Lana Maizel

Advisor: David Schaffner

Studying The Effect of A Blocking Disk on Plasma Turbulence and Magnetic Field Lines

Plasma, in the most simple of terms, is a superheated gas which gets so hot that electrons are separated from atoms, forming an electrically charged ionized gas. The majority of the universe is made up of plasma, and this state of matter generally behaves in a chaotic manner called turbulence. Plasma turbulence as a concept is still not yet widely understood, so our experiment seeks to understand how plasma behaves when there is an obstruction placed in front of it. The sun, for example, is composed of plasma, and large gusts of solar winds can extend far past the surface of the sun, carrying plasma to the surface of the moon and beyond. We will model this phenomena in our laboratory by placing a 3 inch x 3 inch ceramic Macor tile in front of the plasma gun within the BMX plasma machine. Since ceramic has no impact on magnetic fields (like the Moon) and can withstand low pressure environments, it is ideal for our experimentation purposes. We predict that, due to the obstruction, there will be no plasma nor magnetic field directly behind the ceramic tile, however we do not know how large this empty gap will be. In a similar vein, we expect both the plasma and magnetic field lines will reconnect some distance away from the obstruction, however the nature of this collision and the state of the turbulence at this collision is still untested. We hope our experiment will provide the scientific community with a greater understanding of not only how certain obstructions can affect magnetic field lines and the path of plasma, but also enrich the scientific understanding of plasma turbulence as a whole.

Nina Martinez Diers

Advisor: Asja Radja

Modeling the Trapping Mechanisms of Drosera capensis

Sundews are carnivorous plants that live in nutrient-poor environments and gain energy by digesting insects. They catch insects in sticky, hair-like cells that cover their leaves, which then signals the overall leaf to fold or curl over the insect, fully digesting it. Once digestion is complete, the leaf reopens back to its original conformation. The underlying mechanism that dictates this folding motion is unknown, however the reversible folding motion has promising implications for the engineering of biomaterials. Known triggers of the trapping motion are chemical stimuli, such as food, or physical stimuli, such as an insect struggling in the hair-like cells. These stimuli induce a variety of trapping motions, including rolling or folding, and our goal is to identify which kinds of stimuli cause which types of trapping mechanism in a handful of different species (all of which have different leaf morphologies). We will then model the morphological transformation of the leaves using particle tracking to analyze time-lapse footage of leaves folding under variable conditions. We will explore how varying the amount of food and the location of food on the leaf results in different trapping motion, and our preliminary results indicate that smaller prey closer to the center of the leaf provoke a folding motion and larger prey closer to the tip of the leaf provoke a curling motion. Finally, we will also use cell-preservation techniques and microscopy to identify what underlying cell changes induce the curvature in the leaf that allows it to trap insects. We hope our model will explain how various triggers induce a variety of trapping motions by tying together leaf geometry, morphological changes, and underlying cellular changes.

Seda Peacher

Advisor: Asja Radja

Turing Patterns in Monkeyflowers

We will be using a modified Gierer Meinhardt model, which is a further developed version of the equations resulting from Alan Turing’s theory of morphogenesis, to model the patterns on the petals of Mimulus, or monkeyflowers. Turing proposed activator-inhibitor equations meant to predict natural patterns, from embryonic development to zebra stripes. His theory was long overlooked, but it has recently captured scientists’ attention. We hope to propose physics-based modifications that will allow models to more accurately represent the actual patterns in the flowers. I will be reproducing and modifying the code from a previous biology experiment using Python. We also hope to find a way to tailor the Gierer Meinhardt equations to these flowers specifically in an attempt to produce more accurate results. I will be testing our modifications in Python as well.

Ellie Rivera

Advisor: Asja Radja

Gorgonian Coral Morphology and Resulting Flow Fields

Coral reefs are integral to marine ecosystems, and rising ocean temperatures resulting from global warming are contributing to coral bleaching and disrupting these systems. Gorgonian corals are the most resilient to climate change, and although the mechanism by which they adapt to these changes isn’t definitively known, it is hypothesized that it may be related to their plastic morphologies and the way they interact with flow fields in their environments. In this project, we will be exploring the flow fields resulting from gorgonian coral morphology using 3D printed model corals in a custom flow tank. Models will be based on scans of live and dried coral samples, and flow fields will be measured using particle image velocimetry (PIV), a technique that uses cameras to record movement oof tracer particles illuminated in a laser plane. Using image analysis in python, we will create velocity maps from this data, which will allow us to understand the flow fields resulting from various gorgonian morphologies.

Sage Thomas and Annick van Blerkom

Advisor: Michael Noel

Density dependence of dipole-dipole interactions among ultracold Rydberg atoms in Stark states

By using laser spectroscopy, Rubidium-85 atoms in a magneto-optical trap can be excited into Rydberg states where they have high principal quantum numbers, n. In this state, the electrons are weakly bound, which allows for energy exchange through long-range dipole-dipole interactions. We have excited the atoms to states within the Stark manifold. Previous studies have investigated the time dependence of this interaction, and we will be investigating the density dependence of this energy exchange.