Characterizing Magnetism and Frustration in Strained Kagome Nanoribbons

Kagome lattices provide a rich playground for exploring the interplay between crystal symmetry and electronic correlations. In this work, we study interacting electrons in a kagome nanoribbon in the presence of uniaxial strain. Employing a Hubbard Hamiltonian and DMRG calculations, we explore the magnetic properties of its ground state at half-filling. As the uniaxial strain breaks the nearest-neighbor (NN) coupling symmetry, the accompanying suppression of geometric frustration induces distinct magnetic orderings in the system that depend on the direction of the applied strain. The system exhibits coexisting paramagnetic and anti-ferromagnetic behavior for specific strain orientations, weak applied magnetic fields, and Hubbard interaction strength. To help characterize the different quantum phases we compare three distinct ways of quantifying frustrations: (i) a parametric frustration index (PFI), solely dictated by the statistical dispersion of NN hoppings; (ii) a local quantum FI, based on how a given lattice site is entangled with the rest of the system; and (iii) a local geometrical FI, that averages how much a site is capable of attaining full anti- or ferromagnetic order with its neighbors. Their use for classification and predictive powers is confronted with DMRG data.