Topology and magnetism in the Kondo insulator phase diagram

Abstract

Topological Kondo insulators are a rare example of an interaction-enabled topological phase of matter in three-dimensional crystals -making them an intriguing but also hard case for theoretical studies. Here, we aim to advance their theoretical understanding by solving the paradigmatic two-band model for topological Kondoinsulators using a fully spin-rotation invariant slave-boson treatment. Within a mean-field approximation, we map out the magnetic phase diagram and characterize both antiferromagnetic and paramagnetic phases by their topological properties. Among others, we identify an antiferromagnetic insulator that shows, for suitable crystal terminations, topologically protected hinge modes. Furthermore, Gaussian fluctuations of the slave boson fields around their mean-field value are included in order to establish the stability of the mean-field solution through computation of the full dynamical susceptibility. arXiv:1911.11217v1 [cond-mat.str-el]

Superconductivity in octagraphene

“…In the SBMF approach [94][95][96][97][98][99][100][101] with the effective t-J model, the electron operator c iσ can be replaced by c iσ → f iσ b † i , with the bosonic holon (doublon) operator b † i and the fermionic spinon operator f iσ subject to the no-doubleoccupancy constraint b † i b i + ∑ σ f † iσ f iσ = 1 enforced by the Lagrange multiplier. [94] At zero temperature the condensation of bosonic b † i leads to b † i → √…”