Condensed Matter Theory: publications

Non-reciprocal active-matter: a tale of “loving hate, brawling love” across the scales

Europhysics news EDP Sciences 55:3 (2024) 12-15

Phase ordering in binary mixtures of active nematic fluids

Phys. Rev. E 110, 024607 (August 2024)

Authors:

Saraswat Bhattacharyya and Julia M Yeomans

Abstract:

We use a continuum, two-fluid approach to study a mixture of two active nematic fluids. Even in the absence of thermodynamically-driven ordering, for mixtures of different activities we observe turbulent microphase separation, where domains form and disintegrate chaotically in an active turbulent background. This is a weak effect if there is no elastic nematic alignment between the two fluid components, but is greatly enhanced in the presence of an elastic alignment or substrate friction. We interpret the results in terms of relative flows between the two species which result from active anchoring at concentration gradients. Our results may have relevance in interpreting epithelial cell sorting and the dynamics of multi-species bacterial colonies.

Finite-Entanglement Scaling of 2D Metals

Physical Review Letters American Physical Society (APS) 131:26 (2023) 266202

Authors:

Quinten Mortier, Ming-Hao Li, Jutho Haegeman, Nick Bultinck

Operator dynamics in Floquet many-body systems

(2023)

Authors:

Takato Yoshimura, Samuel J Garratt, JT Chalker

Resurgence of superconductivity and the role of dxy hole band in FeSe1−xTex

Communications Physics Springer Nature 6:1 (2023) 362

Authors:

Archie B Morfoot, Timur K Kim, Matthew D Watson, Amir A Haghighirad, Shiv J Singh, Nick Bultinck, Amalia I Coldea

Abstract:

Iron-chalcogenide superconductors display rich phenomena caused by orbital-dependent band shifts and electronic correlations. Additionally, they are potential candidates for topological superconductivity due to the band inversion between the Fe d bands and the chalcogen p_z band. Here we present a detailed study of the electronic structure of the nematic superconductors FeSe_1−xTe_x (0 < x < 0.4) using angle-resolved photoemission spectroscopy to understand the role of orbital-dependent band shifts, electronic correlations and the chalcogen band. We assess the changes in the effective masses using a three-band low energy model, and the band renormalization via comparison with DFT band structure calculations. The effective masses decrease for all three-hole bands inside the nematic phase, followed by a strong increase for the band with d_xy orbital character. Interestingly, this nearly-flat d_xy band becomes more correlated as it shifts towards the Fermi level with increasing Te concentrations and as the second superconducting dome emerges. Our findings suggests that the d_xy hole band, which is very sensitive to the chalcogen height, could be involved in promoting an additional pairing channel and increasing the density of states to stabilize the second superconducting dome in FeSe_1−xTe_x. This simultaneous shift of the d_xy hole band and enhanced superconductivity is in contrast with FeSe_1−xS_x.

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