Wigner Crystals
We study the dynamics of Wigner crystals in solid state systems
using a classical particle-based model. Wigner crystal formation
can have implications for metal-insulator transitions, and has
been proposed to occur in two-dimensional electron gases in
a variety of systems including liquid helium. Recent evidence suggests
that Wigner crystals may occur in monolayer semiconductors and
dichalcogenide monolayers, moire heterostructures, and oxides,
while it has been suggested that bilayer Wigner crystals may form
in dichalcogenide heterostructures. A major question that we address
is what is the role of quenched disorder in Wigner crystal phases
and dynamics.
Preprints:
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Depinning, melting and sliding of generalized Wigner crystals in moire systems
C. Reichhardt and C.J.O. Reichhardt
We numerically examine the depinning, sliding, and melting of commensurate and incommensurate Wigner crystals on two-dimensional hexagonal periodic substrates near fillings of 1/3, 1/2, and 2/3 to model the dynamics of generalized Wigner crystals in moire heterostructures. At low temperatures where thermal fluctuations are irrelevant, for commensurate fillings we find a strongly pinned state that depins into a sliding crystal, while at incommensurate fillings, the depinning threshold is strongly reduced. For fillings below 1/2, the depinning occurs in a two-step process. Above the first depinning threshold, there is an extended range of drives where the conduction occurs via the sliding of anti-kinks along the charge stripes, followed by a second threshold where all of the charges begin to slide. At finite temperatures, the external driving reduces the effective melting temperature at commensurate fillings and enhances creep at incommensurate fillings. We show that depinning into different sliding states, such as moving fluids or moving crystals, produces nonlinear features in the transport curves. We also show that transport is asymmetric on either side of a commensurate filling due to the different dynamics for interstitials versus holes in the commensurate structure. A variety of sliding states should be accessible for generalized Wigner crystals at finite temperatures even for low drives. If experiments can realize sliding dynamics in moire systems, it would open a new class of commensurate and incommensurate phases for study. Additionally, the sliding dynamics and anti-kink flow could provide new functionalities for charge transport in moire heterostructures.
arXiv
Papers:
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Magnetic field effects and transverse ratchets in charge lattices coupled to asymmetric substrates
C.J.O. Reichhardt and C. Reichhardt
New J. Phys. 25, 113038 (2023).
arXiv
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Collective dynamics and defect generation for Wigner crystal ratchets
C. Reichhardt and C.J.O. Reichhardt
Phys. Rev. B 108, 0155131 (2023).
arXiv
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Noise and thermal depinning of Wigner crystals
C. Reichhardt and C.J.O. Reichhardt
J. Phys.: Condens. Matter 35, 325603 (2023).
arXiv
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Melting, reentrant ordering and peak effect for Wigner crystals with quenched and thermal disorder
C. Reichhardt and C.J.O. Reichhardt
New J. Phys. 25, 043016 (2023).
arXiv
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Nonlinear dynamics, avalanches and noise for driven Wigner crystals
C. Reichhardt and C.J.O. Reichhardt
Phys. Rev. B 106, 235417 (2022).
arXiv
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Drive dependence of the Hall angle for a sliding Wigner crystal in a magnetic field
C. Reichhardt and C.J.O. Reichhardt,
Phys. Rev. B 103, 125107 (2021).
arXiv
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Noise at the crossover from Wigner liquid to Wigner glass
C. Reichhardt and C.J. Olson Reichhardt,
Phys. Rev. Lett. 93, 176405 (2004). arXiv
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Moving Wigner glasses and smectics: Dynamics of disordered Wigner
crystals
C. Reichhardt, C.J. Olson, N. Gronbech-Jensen, and F. Nori,
Phys. Rev. Lett. 86, 4354 (2001). arXiv
Last modified Nov 17, 2023