Geometrical-Frustration-Induced (Semi)Metal-to-Insulator Transition

Abstract

We study the low-energy properties of the geometrically frustrated Hubbard model on a three-dimensional pyrochlore lattice and a two-dimensional checkerboard lattice on the basis of the renormalization group method and mean field analysis. It is found that, in the half-filling case, a (semi)metal to insulator transition (MIT) occurs. Also, in the insulating phase, which has a spin gap, the spin rotational symmetry is not broken, while charge ordering exists. The results are applied to the description of the MIT observed in the pyrochlore system [Formula presented]. © 2002 The American Physical Society.