---
_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). <i>Magnetic force microscopy studies of mesoscopic superconducting
    structures</i>. 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. <i>Magnetic Force Microscopy Studies of Mesoscopic Superconducting
    Structures</i>. 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'
...