Zero finite-temperature charge stiffness within the half-filled 1D Hubbard model Original Research Article

Even though the one-dimensional (1D) Hubbard model is solvable by the Bethe ansatz, at half-filling its finite-temperature image transport properties remain poorly understood. In this paper we combine that solution with symmetry to show that within that prominent image 1D insulator the charge stiffness image vanishes for image and finite values of the on-site repulsion image in the thermodynamic limit. This result is exact and clarifies a long-standing open problem. It rules out that at half-filling the model is an ideal conductor in the thermodynamic limit. Whether at finite image and image it is an ideal insulator or a normal resistor remains an open question. That at half-filling the charge stiffness is finite at image and vanishes for image is found to result from a general transition from a conductor to an insulator or resistor occurring at image for all finite temperatures image. (At image such a transition is the quantum metal to Mott–Hubbard-insulator transition.) The interplay of the image-spin image symmetry with the hidden image symmetry beyond image is found to play a central role in the unusual finite-temperature charge transport properties of the 1D half-filled Hubbard model.