Quantum paramagnet in a $\ddot{I}€$ flux triangular lattice Hubbard model

Abstract

We propose the $\ddot{I}€$ flux triangular lattice Hubbard model ($\ddot{I}€$-THM) as a prototypical setup to stabilize magnetically disordered quantum states of matter in the presence of charge fluctuations. The quantum paramagnetic domain of the $\ddot{I}€$-THM which we identify for intermediate Hubbard U is framed by a Dirac semi-metal for weak coupling and by 120${}^{\circ }$ Néel order for strong coupling. Generalizing the Klein duality from spin Hamiltonians to tight-binding models, the $\ddot{I}€$-THM maps to a Hubbard model which corresponds to the $(J_H,J_K)=(-1,2)$ Heisenberg-Kitaev model in its strong coupling limit. The $\ddot{I}€$-THM provides a promising microscopic testing ground for exotic finite-U spin liquid ground states amenable to numerical investigation.

4+e pages, 3 figures; version to appear in Phys. Rev. Lett