Speaker

Dr. Fengfeng Song  / The University of Tokyo

Title

Superfluid dome in the spatially modulated two-dimensional XY model

Abstract

In strongly correlated electron systems, superconductivity and charge density waves often coexist in close proximity, suggesting a deeper relationship between these competing phases. Recent research indicates that these orders can intertwine, with the superconducting order parameter coupling to modulations in the electronic density. To elucidate this interplay, we study a two-dimensional XY model with a periodic modulation of the coupling strength in one spatial direction. Using a combination of tensor network methods and Monte Carlo simulations, we reveal a non-monotonic, dome-like dependence of Tc on the modulation wavelength, with the peak Tc shifting to longer wavelengths as the modulation strength grows. The origin of this phenomenon is traced back to an effective pinning of vortices in the valleys of the modulation, confirmed by a comparison to modulated q-state clock models. These findings shed new light on the phase behavior of intertwined superconducting and charge-ordered states, offering a deeper understanding of their complex interactions.

Profile of Speaker

Feng-Feng Song is a Project Researcher at the Institute for Solid State Physics, the University of Tokyo. His research focuses on frustrated magnetic systems and phase coherence phenomena in superconductors, using tensor network methods.

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