Magnetic reversal of artificial spin ice

Park, Jungsik

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https://hdl.handle.net/2142/101746 Copy

Description

Title

Magnetic reversal of artificial spin ice

Author(s)

Park, Jungsik

Issue Date

2018-05-24

Director of Research (if dissertation) or Advisor (if thesis)

Schiffer, Peter

Doctoral Committee Chair(s)

Mason, Nadya

Committee Member(s)

• Cahill, David
• Peng, Jen-Chieh

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Artificial spin ice
• Magnetotransport

Abstract

Artificial spin ice refers to an array of elongated ferromagnetic elements, providing a fascinating model system to study novel magnetic behavior induced by frustration. Initially used as a tool to understand the behavior of the frustrated spin systems called spin ice, artificial spin ice has become an independent research area in its own right. The advantage of artificial spin ice compared to its natural counterpart is that one can vary the interaction strength and geometry at will. In my dissertation, I will describe a series of experimental studies that center around the magnetic reversal of artificial spin ice arrays. First, I investigate the magnetic response of permalloy brickwork artificial spin ice. Through the systematic study of the transport properties for finely varied magnetic field directions, I find that the vertices of connected brickwork artificial spin ice control its transport characteristics despite their relatively small extent. In addition, I find that the ground state of the system can be achieved by a single field sweep when the angle of the magnetic field was precisely oriented, in both connected and disconnected systems. The ground state formation of the connected brickwork artificial spin ice manifests itself in its unique magnetoresistance properties; the magnetotransport behavior abruptly changes when the applied field angle changes a little bit around the symmetry axis. Second, the magnetic avalanche study on disconnected square artificial spin ice will be presented. The magnetic force microscopy (MFM) study allows for the direct observation and characterization of one-dimensional Dirac strings. Finally, an attempt to study the thermally-assisted magnetization reversal of connected kagome artificial spin ice will be demonstrated. I found the potentially interesting thermally-activated behavior from the transport measurement on the frustrated system. Investigations mentioned above illustrate the utility of artificial spin ice as a metamaterial in which to study a variety of fascinating physics.

Graduation Semester

2018-08

Type of Resource

text

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http://hdl.handle.net/2142/101746

Copyright and License Information

©2018 by Jungsik Park. All rights reserved

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