---
_id: '10663'
abstract:
- lang: eng
text: 'The superconducting state of matter enables one to observe quantum effects
on the macroscopic scale and hosts many fascinating phenomena. Topological defects
of the superconducting order parameter, such as vortices and fluxoid states in
multiply connected structures, are often the key ingredients of these phenomena.
This dissertation describes a new mode of magnetic force microscopy (Φ0-MFM) for
investigating vortex and fluxoid sates in mesoscopic superconducting (SC) structures.
The technique relies on the magneto-mechanical coupling of a MFM cantilever to
the motion of fluxons. The novelty of the technique is that a magnetic particle
attached to the cantilever is used not only to sense the state of a SC structure,
but also as a primary source of the inhomogeneous magnetic field which induces
that state. Φ0-MFM enables us to map the transitions between tip-induced states
during a scan: at the positions of the tip, where the two lowest energy states
become degenerate, small oscillations of the tip drive the transitions between
these states, which causes a significant shift in the resonant frequency and dissipation
of the cantilever. For narrow-wall aluminum rings, the mapped fluxoid transitions
form concentric contours on a scan. We show that the changes in the cantilever
resonant frequency and dissipation are well-described by a stochastic resonance
(SR) of cantilever-driven thermally activated phase slips (TAPS). The SR model
allows us to experimentally determine the rate of TAPS and compare it to the Langer-Ambegaokar-McCumber-Halperin
(LAMH) theory for TAPS in 1D superconducting structures. Further, we use the SR
model to qualitatively study the effects of a locally applied magnetic field on
the phase slip rate in rings containing constrictions. The states with multiple
vortices or winding numbers could be useful for the development of novel superconducting
devices, or the study of vortex interactions and interference effects. Using Φ0-MFM
allows us to induce, probe and control fluxoid states in thin wall structures
comprised of multiple loops. We show that Φ0-MFM images of the fluxoid transitions
allow us to identify the underlying states and to investigate their energetics
and dynamics even in complicated structures.'
alternative_title:
- Graduate Dissertations and Theses at Illinois
article_processing_charge: No
author:
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
citation:
ama: Polshyn H. Magnetic force microscopy studies of mesoscopic superconducting
structures. 2017.
apa: Polshyn, H. (2017). Magnetic force microscopy studies of mesoscopic superconducting
structures. University of Illinois at Urbana-Champaign.
chicago: Polshyn, Hryhoriy. “Magnetic Force Microscopy Studies of Mesoscopic Superconducting
Structures.” University of Illinois at Urbana-Champaign, 2017.
ieee: H. Polshyn, “Magnetic force microscopy studies of mesoscopic superconducting
structures,” University of Illinois at Urbana-Champaign, 2017.
ista: Polshyn H. 2017. Magnetic force microscopy studies of mesoscopic superconducting
structures. University of Illinois at Urbana-Champaign.
mla: Polshyn, Hryhoriy. Magnetic Force Microscopy Studies of Mesoscopic Superconducting
Structures. University of Illinois at Urbana-Champaign, 2017.
short: H. Polshyn, Magnetic Force Microscopy Studies of Mesoscopic Superconducting
Structures, University of Illinois at Urbana-Champaign, 2017.
date_created: 2022-01-25T14:54:14Z
date_published: 2017-09-18T00:00:00Z
date_updated: 2022-01-25T15:00:26Z
day: '18'
degree_awarded: PhD
extern: '1'
keyword:
- physics
- superconductivity
- magnetic force microscopy
- phase slips
language:
- iso: eng
main_file_link:
- open_access: '1'
url: http://hdl.handle.net/2142/99178
month: '09'
oa: 1
oa_version: Published Version
page: '103'
publication_status: published
publisher: University of Illinois at Urbana-Champaign
status: public
supervisor:
- first_name: Raffi
full_name: Budakian, Raffi
last_name: Budakian
title: Magnetic force microscopy studies of mesoscopic superconducting structures
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2017'
...