Sergio E. Ulloa (Ohio University)

Date: Mon. December 2nd, 2024, 12:45 pm-1:45 pm
Location: Rock 221 (Foldy room) & Zoom
Website: https://scholar.google.de/citations?user=uZQ1RBgAAAAJ&hl=en

Tuning correlations by uniaxial strain in kagome lattices

Sergio E. Ulloa

Department of Physics and Astronomy,  Ohio University

Abstract: Topological and correlated phases arise in kagome lattices associated with Dirac fermions and flat dispersions in the single-particle energy spectrum. We have studied the interplay of attractive electron interactions and topological states in strained kagome lattices at different band-filling factors. The system is known to be driven into a charge density wave state beyond a critical attractive interaction U_c. We study the tunability of U_c employing uniaxial strains and doping levels and find different phases as these physical parameters change. As uniaxial strain breaks the C₃ symmetry of the lattice, we see the onset of a charge density wave ground state even for weak attractive interaction. With spin-orbit interaction, the system changes from a quantum spin Hall state to a charge density wave at U_c.  We find a region of strain and interaction values where the two phases coexist before increasing strain results in a pure charge density state. When pairing correlations are allowed, we find competition between a superconducting gap and that related to the charge modulation. For repulsive interactions in nanoribbons, we study how the strain direction affects the formation of singlets in neighboring sites. Our aim is to explore how electronic correlations and single-particle topological structures compete to create fascinating correlated phases in kagome systems.

 

Host: Walter Lambrecht