Zero finite-temperature charge stiffness within the half-filled 1D Hubbard model |
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Authors: | JMP Carmelo Shi-Jian Gu PD Sacramento |
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Institution: | 1. Center and Department of Physics, University of Minho, Campus Gualtar, P-4710-057 Braga, Portugal;2. Beijing Computational Science Research Center, Beijing 100084, China;3. Institut für Theoretische Physik III, Universität Stuttgart, D-70550 Stuttgart, Germany;4. Department of Physics and ITP, Chinese University of Hong Kong, Hong Kong, China;5. CFIF, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal |
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Abstract: | Even though the one-dimensional (1D) Hubbard model is solvable by the Bethe ansatz, at half-filling its finite-temperature T>0 transport properties remain poorly understood. In this paper we combine that solution with symmetry to show that within that prominent T=0 1D insulator the charge stiffness D(T) vanishes for T>0 and finite values of the on-site repulsion U 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 T and U>0 it is an ideal insulator or a normal resistor remains an open question. That at half-filling the charge stiffness is finite at U=0 and vanishes for U>0 is found to result from a general transition from a conductor to an insulator or resistor occurring at U=Uc=0 for all finite temperatures T>0. (At T=0 such a transition is the quantum metal to Mott-Hubbard-insulator transition.) The interplay of the η-spin SU(2) symmetry with the hidden U(1) symmetry beyond SO(4) is found to play a central role in the unusual finite-temperature charge transport properties of the 1D half-filled Hubbard model. |
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