We simulate the motion of a commensurate vortex lattice in a periodic lattice of artificial circular pinning sites having different diameters, pinning strengths, and spacings using the time-dependent Ginzburg-Landau formalism. Above some critical DC current density Jc, the vortices depin, and the resulting steady-state motion then induces an oscillatory electric field E (t) with a defect "hopping" frequency f0, which depends on the applied current density and the pinning landscape characteristics. The frequency generated can be locked to an applied AC current density over some range of frequencies, which depends on the amplitude of the DC as well as the AC current densities. Both synchronous and asynchronous collective hopping behaviors are studied as a function of the supercell size of the simulated system and the (asymptotic) synchronization threshold current densities determined.
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This content will become publicly available on March 1, 2025
Ginzburg-Landau approach to the vortex–domain wall interaction in superconductors with nematic order
In this work, we study the interaction between vortices and nematic domain walls within the framework of
a Ginzburg-Landau approach. The free energy of the system is written in terms of a complex order parameter
characteristic of s-wave superconductivity and a real (Ising-type) order parameter associated with nematicity.
The interaction between both order parameters is described by a biquadratic and a trilinear derivative term. To
study the effects of these interactions, we solve the time-dependent dissipative Ginzburg-Landau equations using
a highly effective pseudospectral method by which we calculate the trajectories of a vortex that, for different
coupling parameters, is either attracted or repelled by a wall, as well as of the wall dynamics. We show that
despite its simplicity, this theory displays many phenomena observed experimentally in Fe-based superconductors.
In particular, we find that the sign of the biquadratic term determines the attractive (pinning) or repulsive
(antipinning) character of the interaction, as observed in FeSe and BaFeCoAs compounds, respectively. The
trilinear term is responsible for the elliptical shape of vortex cores as well as the orientation of the axes of
the ellipses and vortex trajectories with respect to the axes of the structural lattice. For the case of pinning, we
show that the vortex core is well described by a heart-shaped structure in agreement with scanning tunneling
microscopy experiments performed in FeSe.
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- Award ID(s):
- 2225920
- NSF-PAR ID:
- 10496680
- Publisher / Repository:
- Physical Review B
- Date Published:
- Journal Name:
- Physical Review B
- Volume:
- 109
- Issue:
- 9
- ISSN:
- 2469-9950
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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