Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 15: Correlated Electrons: Metal-Insulator Transition 2

TT 15.10: Vortrag

Dienstag, 24. März 2009, 12:15–12:30, HSZ 301

Quantum Monte Carlo study of the half-filled Hubbard model on the honeycomb lattice — •Zi Yang Meng¹, Thomas C. Lang², Stefan Wessel¹, Fakher F. Assaad², and Alejandro Muramatsu¹ — ¹Institut für Theoretische Physik III, Universität Stuttgart, Germany — ²Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany

Using projective (T=0) quantum Monte Carlo we investigate the ground-state properties of the half-filled Hubbard model on a honeycomb lattice. Our results confirm previous numerical findings[1] that antiferromagnetic long-range order sets in above a value of U/t≈ 4.5. However, examining the quasiparticle gap and the spin gap, we obtain preliminary indications, that the Mott-transition from the semi-metal to an insulator occurs at a value of U/t≈ 3.5. A separation of two phase transitions allows for the possibility of an intermediate phase between the semi-metal and the antiferromagnetic insulator – a scenario, that has been discussed in recent theoretical studies[2,3]. Further numerical work, aiming at testing such propoals is in progress.

[1] S. Sorella and E. Tosatti, Europhys. Lett. 19, 699 (1992).

[2] M. Hermele, Phys. Rev. B 76, 035125 (2007).

[3] B. Uchoa and A. H. C. Neto, Phys. Rev. Lett. 98, 146801 (2007).