Lifting Degeneracy in the Vortex Lattice of MgB<sub>2</sub>
ORAL
Abstract
The superconducting vortex lattice (VL) of MgB2 hosts three structural phases associated with
distinct rotations of the VL with respect to the crystal lattice. One of these phases, the L phase, contains two
degenerate orientations with respect to the a axis, causing the VL to fracture into domains. Domain boundaries
inhibit structural transitions to and from the L phase, giving rise to robust metastability and an activation barrier
which grows rapidly as the VL approaches equilibrium [1]. These domain-dominated kinetics are ubiquitous in
material science, from martensitic phase transitions to ferroelectric domain switching, however, unique to the
VL of MgB2 is the ability to externally tune this behavior. By rotating the crystal with respect to the applied field,
we can suppress the geometric degeneracy between the two domain orientations and inhibit domain wall
formation. In this talk, we will discuss the effect of this broken symmetry on both the VL phase diagram and the
kinetic behavior of the structural phase transitions.
[1] E. R. Louden et al., Phys. Rev. B 99, 060502(R) (2019); ibid. 99, 144515 (2019).
distinct rotations of the VL with respect to the crystal lattice. One of these phases, the L phase, contains two
degenerate orientations with respect to the a axis, causing the VL to fracture into domains. Domain boundaries
inhibit structural transitions to and from the L phase, giving rise to robust metastability and an activation barrier
which grows rapidly as the VL approaches equilibrium [1]. These domain-dominated kinetics are ubiquitous in
material science, from martensitic phase transitions to ferroelectric domain switching, however, unique to the
VL of MgB2 is the ability to externally tune this behavior. By rotating the crystal with respect to the applied field,
we can suppress the geometric degeneracy between the two domain orientations and inhibit domain wall
formation. In this talk, we will discuss the effect of this broken symmetry on both the VL phase diagram and the
kinetic behavior of the structural phase transitions.
[1] E. R. Louden et al., Phys. Rev. B 99, 060502(R) (2019); ibid. 99, 144515 (2019).
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Presenters
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Allan Leishman
Department of Physics, University of Notre Dame
Authors
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Allan Leishman
Department of Physics, University of Notre Dame
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Morten Eskildsen
Department of Physics, University of Notre Dame, University of Notre Dame
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Nikolai D Zhigadlo
CrystMat Company, Zurich, Switzerland, University of Bern
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Markus Bleuel
Center for Neutron Research, National Institute of Standards and Technology, National Institute of Standards and Technology Center for Neutron Research, NIST, NIST Center for Neutron Research, National Institute of Standards and Technology, National Institute of Standards and Technology