Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 48: Poster Session II
MA 48.67: Poster
Donnerstag, 10. März 2016, 15:00–18:00, Poster B1
Ab initio analysis of the topological phase diagram of the Haldane model — •Julen Ibañez-Azpiroz1, Asier Eiguren2, Aitor Bergara2, Giulio Pettini3, and Michele Modugno2 — 1Peter Grunberg Institute and Institute for Advanced Simulation, Forschungszentrum Julich — 2University of the Basque Country UPV/EHU — 3Dipartimento di Fisica e Astronomia, Universita di Firenze
We present an ab initio analysis of a continuous Hamiltonian that maps into the celebrated Haldane model. The tunnelling coefficients of the tight-binding model are computed by means of two independent methods - one based on the maximally localized Wannier functions, the other through analytic expressions in terms of gauge-invariant properties of the spectrum - that provide a remarkable agreement and allow to accurately reproduce the exact spectrum of the continuous Hamiltonian. Our calculations show that the commonly employed Peierls substitution for the complex tunneling coefficient does not provide a reasonable estimate, and we discuss the origin of this feature. Additionally, by combining these results with the numerical calculation of the Chern number, we are able to draw the phase diagram in terms of the physical parameters of the microscopic model. Remarkably, we find that only a small fraction of the original phase diagram of the Haldane model can be accessed, and that the topological insulator phase is suppressed in the deep tight-binding regime.