Keshab Sony | Searcharxiv

arXiv2026

Approximate vortex lattices of atomic Fermi superfluid on a spherical surface

While planar Fermi superfluids form Abrikosov vortex lattices under magnetic or effective gauge fields, spherical geometry forbids perfect lattices above 20 vortices. We characterize approximate vortex structures of atomic Fermi superfluids under an effective monopole field on a spherical surface as an analogue of the planar vortex-lattice problem by two constructions based on the Ginzburg-Landau theory. The first one is geometric and uses the random, geodesic-dome, and Fibonacci lattices as scaffolds to construct the order parameter from the degenerate monopole harmonics. The second one minimizes the free energy by numerically adjusting the coefficients to find the solution with the minimal Abrikosov parameter. We have verified the vortices from both constructions are zeros of the order parameter with circulating currents around the vortex cores. As the number of vortices increases, the Abrikosov parameters of both the Fibonacci-lattice and minimization solutions extrapolate to the planar value. We briefly discuss implications for ultracold atoms in thin spherical-shell geometry.

cond-mat.quant-gas↗

arXiv2024

Strictly one dimensional behavior emerging from dispersive two dimensional system: implications on metallic nanowires on semiconducting substrates

We studied single and two Su-Shreiffer-Heeger wires on a simple cubic semiconducting substrate. The wire-wire coupling is either perpendicular or diagonal hopping respecting the particle-hole and time-reversal symmetries. The hybridization to the substrate renormalizes the model parameters of the wires towards the hopping parameter of the substrate without changing the basic nature of perpendicular or diagonal coupling and it can mediate effective perpendicular hopping but not diagonal hopping in the absence of direct wire-wire coupling. This justifies the investigation of multi uniform tight binding wires with perpendicular or diagonal hopping parameters while neglecting the substrate. Perpendicularly coupled uniform wires reveal an anisotropic two dimensional band dispersion. Diagonally coupled uniform wires reveal strictly one dimensional bands parallel to the wires direction if the intra-wire hopping parameter is larger than twice the diagonal hopping parameter despite strong dispersion perpendicular to the wires. Otherwise, they reveal strictly one dimensional bands parallel and perpendicular to the wires direction simultaneously. We established the possibility of realizing strictly one dimensional properties emerging from dispersive two dimensional systems if time-reversal and particle-hole symmetries are respected. This can facilitate the investigations of Luttinger liquid in the Au/Ge(001) and Bi/InSb(001) surface reconstructions.

cond-mat.mes-hall↗