University of Illinois Urbana-Champaign

Imaging magnetic order in magneto-structural phases of Mn3O4

Wang, Xu

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https://hdl.handle.net/2142/42427

Description

Title
Imaging magnetic order in magneto-structural phases of Mn3O4
Author(s)
Wang, Xu
Issue Date
2013-02-03T19:38:08Z
Director of Research (if dissertation) or Advisor (if thesis)
Budakian, Raffi
Doctoral Committee Chair(s)
Giannetta, Russell W.
Committee Member(s)
  • Budakian, Raffi
  • DeMarco, Brian L.
  • Phillips, Philip W.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • strongly correlated materials
  • magnetic frustration
  • phase separation
  • magnetic force microscopy
  • structural phase transition
Abstract
Frustration in A-site spinels due to the competition between complex structure and strong interactions has been the focus of many theoretical and experimental studies recently. Mn3O4 is one such material with a three way interplay between complex lattice geometry, strong spin-lattice coupling and magnetic interactions. Mn3O4 is known to have two distinct phases below the Neel temperature that differ in both structure and magnetic order, including a tetragonal phase with disordered spins, and at lower temperatures, an orthorhombic phase exhibiting long-range commensurate magnetic order. Using a combination of low temperature magnetic force microscopy and electron backscatter diffraction techniques, we explore this magneto-structural phase transition in Mn3O4 at 33K. Novel sub-micron magnetic patterns emerge upon transition, and are aligned with specific crystalline axis directions. These magnetic patterns show variations with temperature and magnetic field. We attribute the magnetic patterns observed to strain-mediated phase separation. Phases are separated by a unique wall type, stabilized by the magneto-elastic coupling in Mn3O4. This result and the technique developed enable study of similar phase separation behaviors in related strongly correlated materials.
Graduation Semester
2012-12
Permalink
http://hdl.handle.net/2142/42427
Copyright and License Information
Copyright 2012 Xu Wang

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