Project Info


Voretx Dynamics in Superconductors at High Vortex Densities

Serena Eley | serenaeley@mines.edu

The current carrying capacity Jc of type-II superconductors is severely limited by dissipation from the motion of vortices, magnetic flux lines that appear inside these materials upon immersion in sufficiently high magnetic fields. To date, no superconductor has achieved a Jc higher than ~25-30% its theoretical maximum Jd. Incorporating nanoparticle inclusions into superconducting films is a well-established route for boosting Jc because defects can trap vortices. In fact, superconductors containing nanoparticles have produced some of the highest critical currents, hence, this growth technique shows promise for producing next-generation superconductors with critical currents near Jd. To achieve this, we need to garner a better understanding of vortex-nanoparticle and vortex-vortex interactions, the latter of which is thought to be requisite for attaining Jd. Recent results from time-dependent Ginzburg-Landau simulations show that the magnetic-field dependence of the critical current strongly depends on the number of vortices captured by individual inclusions, and specifically predict a small dip in Jc(B) at high fields as the signature of inclusions having trapped two vortices.
In this project, the undergraduate researcher will learn about superconductivity (with a focus on vortex dynamics) and low temperature magnetometry. The student will measure the critical current and vortex creep in superconducting (Y,Gd)Ba2Cu3O7-x films and iron-based films containing various densities of nanoparticles using a local magnetometer then characterize the films in higher magnetic fields at the National High Magnetic Field Lab (NHMFL) in Florida. Specifically, the student will look for the signature of inclusions capturing more than one vortex by performing magnetization measurements in cell 12 (35 T magnet) at the NHMFL in May. We will then make correlations between the nanoparticle density, size relative to the coherence length, and the appearance of non-monotonicity in Jc(B).

More Information

1. Foltyn, S. R. et al. Materials science challenges for high-temperature superconducting wire. Nature Mater. 6, 631–642 (2007).
2. Kwok, W.-K. et al. Vortices in high-performance high-temperature superconductors. Rep. Prog. Phys. 79, 116501 (2016).
3. Yeshurun, Y., Malozemoff, A. P. & Shaulov, A. Magnetic relaxation in high- temperature superconductors. Rev. Mod. Phys. 68, 911–949 (1996).
4. Miura, M. et al. Mixed pinning landscape in nanoparticle-introduced YGdBa2- Cu3Oy films grown by metal organic deposition. Phys. Rev. B 83, 184519 (2011)
5. Willa, R., Koshelev, A. E., Sadovskyy, I. A. & Glatz, A. Strong-pinning regimes by spherical inclusions in anisotropic type-II superconductors. Supercond. Sci. Technol. 31, 014001 (2018).
6. Introduction to Superconductivity by Michael Tinkham
7. Blatter, G., Feigel’man, M. V., Geshkenbein, V. B., Larkin, A. I. & Vinokur, V. M. Vortices in high-temperature superconductors. Rev. Mod. Phys. 66, 1125–1388 (1994).

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Student Preparation


Qualifications

Introductory Quantum Mechanics
Electricity and Magnetism

Time Commitment

25-30 hours/month

Skills/Techniques Gained

Low-temperature measurement
Magnetometry
Cryogenics
Data Analysis using Origin

Mentoring Plan

1. Weekly group meeting during which the student is expected to present results and demonstrate an increasing understanding of materials issues in superconductor applications
2. The professor will accompany the student to a local facility containing a magnetometer, train the student in magnetometer operation, and assist with data collection in preparation for the NHMFL experiment. (The frequency of the trips is to be determined).
3. One-on-one meetings once every 2 weeks