The spin and electronic spectra of the two-dimensional Hubbard model doped away from half-filling (n\ensuremath{\simeq}0.9) are calculated in a conserving fluctuation-exchange approximation for coupling U/t up to 7 and temperature down to 30 K. We find neither a spin-density wave nor a superconducting instability. The energy of the overdamped collective spin mode decreases as T decreases and U/t increases. The Wiedemann-Franz ratio of the thermal and electrical conductivities becomes smaller than the Sommerfeld value. We make comparison with experimental data on cuprates.The spin and electronic spectra of the two-dimensional Hubbard model doped away from half-filling (n\ensuremath{\simeq}0.9) are calculated in a conserving fluctuation-exchange approximation for coupling U/t up to 7 and temperature down to 30 K. We find neither a spin-density wave nor a superconducting instability. The energy of the overdamped collective spin mode decreases as T decreases and U/t increases. The Wiedemann-Franz ratio of the thermal and electrical conductivities becomes smaller than the Sommerfeld value. We make comparison with experimental data on cuprates.

Physical review. B, Condensed matterJan 1, 199429 citations

Scaling of electrical and thermal conductivities in an almost integrable chain

Yichen Huang, Christoph Karrasch, Joel E. Moore

Many low-dimensional materials are well described by integrable one-dimensional models such as the Hubbard model of electrons or the Heisenberg model of spins. However, the small perturbations to these models required to describe real materials are expected to have singular effects on transport quantities: integrable models often support dissipationless transport, while weak nonintegrable terms lead to finite conductivities. We use matrix-product-state methods to obtain quantitative values of spin/electrical and thermal conductivities in an almost integrable gapless ( $XXZ$ -like) spin chain. At low temperatures, we observe power laws whose exponents are solely determined by the Luttinger liquid parameter. This indicates that our results are independent of the actual model under consideration.Many low-dimensional materials are well described by integrable one-dimensional models such as the Hubbard model of electrons or the Heisenberg model of spins. However, the small perturbations to these models required to describe real materials are expected to have singular effects on transport quantities: integrable models often support dissipationless transport, while weak nonintegrable terms lead to finite conductivities. We use matrix-product-state methods to obtain quantitative values of spin/electrical and thermal conductivities in an almost integrable gapless ($XXZ$-like) spin chain. At low temperatures, we observe power laws whose exponents are solely determined by the Luttinger liquid parameter. This indicates that our results are independent of the actual model under consideration.

arXiv:1212.0012Physical Review BSep 16, 201348 citations

XXZ

-like) spin chain. At low temperatures, we observe power laws whose exponents are solely determined by the Luttinger liquid parameter. This indicates that our results are independent of the actual model under consideration.