arXiv subjects

Mingyan Wang

Publications and source records attributed to Mingyan Wang.

2 recordsLinked to original sources

arXiv2026

Interplay between Quantum Metric and Hybridized Collective Mode in Flat-Band Superfluids

We investigate collective excitations in flat-band superfluids by incorporating the coupled dynamics of pairing (phase and amplitude) and density fluctuations. We demonstrate that for any time-reversal symmetric superfluid system with an isolated flat band, only a single low-energy collective mode emerges in the long-wavelength limit. In contrast to the linearly dispersive Goldstone mode in conventional superfluids, this hybridized mode is gapless at zero momentum but exhibits a quadratic dispersion ($\omega \propto q^2$) at small momenta. We show that the dispersion coefficients of this collective mode are governed by the normal-state quantum metric of the flat band. These analytical predictions are in excellent agreement with numerical calculations. Our results are applicable to any generic $s$-wave flat-band superfluid, provided the flat band is energetically well separated from other dispersive bands.

cond-mat.supr-con↗

arXiv2021

Statistical behaviour of interfaces subjected to curvature flow and torque effects applied to microstructural evolutions

The movement of grain boundaries in pure metals and alloys with a low concentration of dislocations has been historically proved to follow curvature flow behavior. This mechanism is typically known as grain growth (GG). However, recent 3D in-situ experimental results tend to question this global picture concerning the influence of the curvature on the kinetics of interface migration. This article explains, thanks to 2D anisotropic full-field simulations, how the torque effects can complexify these discussions. It is then illustrated that neglecting torque effects in full-field formulations remains potentially a strong hypothesis. The apparent mobility can be much more complex than expected without necessarily questioning the influence of the curvature on the local kinetic equation.

cond-mat.mtrl-sci↗