November 29, 2023
Opportunity 1: Vortex Dynamics in Superconductors
Superconductors are revered for their ability to carry high zero resistance currents below a material- dependent critical current density Jc. In these materials, vortices — whirlpools of supercurrents — form and their motion induces unfavorable energy loss that ultimately limits Jc and causes persistent currents to decay over time. Fortunately, defects in materials can immobilize vortices. This has motivated decades of research developing methods of engineering the material defect landscape in superconductors to increase the strength of vortex pinning, therefore boosting Jc. Yet efficacious materials engineering still alludes us – we cannot reliably predict the electromagnetic properties of real (disordered) superconducting materials. Designing superconductors for applications remains a largely inefficient process of trial and error. This is ultimately because much is still unknown about vortex dynamics.
The student will assist in measurements of Jc and thermally activated vortex motion (creep) in superconductors at a range of cryogenic temperatures and applied magnetic fields.
Tasks will include:
- Measuring magnetization in different superconducting samples using a Quantum Design MPMS3 magnetometer
- Analyzing data using pre-written Python scripts run in OriginPro to extract creep versus temperature and magnetic field
- Reading and interpreting research papers to understand quantum vortex creep
- Comparing collected data to models describing quantum vortex creep
Student Expectations
- Be self-motivated, meticulous, and organized
- Work regular hours
- Take ownership of the project
- Give 10-minute presentations on results and plans at our mandatory weekly group meetings
- Maintain and bring an up-to-date, detailed lab notebook and notebook containing a to-do list to every group meeting
- Keep organized OriginLab files containing results that will be passed along to collaborators
- Conduct regular literature searches
Opportunity 2: Recrystallization Study of Magnetic Material Hosting Skyrmion-Antiskyrmion System
Skyrmions and antiskyrmions are nanoscale swirling textures of magnetic moments that form in certain magnetic materials. They are of interest as information carriers in low-energy spintronic devices. To develop skyrmion-based memory and logic, we must understand skyrmion-defect interactions with two main goals — determining how skyrmions navigate intrinsic material defects and determining how to engineer disorder for optimal device operation. Using ion irradiation, we tuned the disorder landscape in B20-phase FeGe films, inducing amorphous regions within the crystalline matrix. We found that while the crystalline regions hosted skyrmions, the amorphized regions introduced antiskyrmions, such that we created a skyrmion-antiskyrmion system. Such a system is a step towards the development of information storage devices that use skyrmions and antiskyrmions as storage bits and our system may serve as a testbed for theoretically predicted phenomena in skyrmion-antiskyrmion crystals.
We are looking for a student to analyze electron diffraction data collected during an in-situ scanning transmission electron microscopy (STEM) study of the irradiated FeGe epitaxial films. The irradiation process introduced amorphized regions, which are recrystallized during annealing.
Tasks will include:
- plot the data as 2D scans,
- compare data collected at various annealing temperatures,
- and determine quantitatively how the density and/or sizes of amorphized regions changes with annealing temperature.
The results should culminate into a publication and there may be opportunities to continue working in the group, performing cryogenic electrical transport measurements on FeGe Hall bars to study the dynamics of magnetic vortices).
Requirements
- Experience analyzing diffraction data (e.g. x-ray diffraction) through coursework or other opportunities.
Student Expectations
- Be self-motivated, meticulous, and organized
- Be comfortable learning new software (e.g. to assist with analyzing the diffraction data)
- Work regular hours
- Take ownership of the project
- Give 10-minute presentations on results and plans at our mandatory weekly group meetings
- Maintain and bring an up-to-date, detailed lab notebook and notebook containing a to-do list to every group meeting
- Keep organized OriginLab files containing results that will be passed along to collaborators
- Conduct regular literature searches
If interested, please email me your CV.
Serena Eley | University of Washington
Assistant Professor
Department of Electrical & Computer Engineering
185 E. Stevens Way NE, Seattle, WA 98195
805-452-2457 | serename@uw.edu | quantumcreep.mines.edu (to be updated soon)