title: Gross violation of the Wiedemann-Franz law in a quasi-one-dimensional conductor.
abstract: When charge carriers are spatially confined to one dimension, conventional Fermi-liquid theory breaks down. In such Tomonaga-Luttinger liquids, quasiparticles are replaced by distinct collective excitations of spin and charge that propagate independently with different velocities. Although evidence for spin-charge separation exists, no bulk low-energy probe has yet been able to distinguish successfully between Tomonaga-Luttinger and Fermi-liquid physics. Here we show experimentally that the ratio of the thermal and electrical Hall conductivities in the metallic phase of quasi-one-dimensional Li(0.9)Mo(6)O(17) diverges with decreasing temperature, reaching a value five orders of magnitude larger than that found in conventional metals. Both the temperature dependence and magnitude of this ratio are consistent with Tomonaga-Luttinger liquid theory. Such a dramatic manifestation of spin-charge separation in a bulk three-dimensional solid offers a unique opportunity to explore how the fermionic quasiparticle picture recovers, and over what time scale, when coupling to a second or third dimension is restored.
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Wakeham
authors.forename: Alimamy F
authors.initials: AF
authors.lastname: Bangura
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Xu
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Mercure
authors.forename: Martha
authors.initials: M
authors.lastname: Greenblatt
authors.forename: Nigel E
authors.initials: NE
authors.lastname: Hussey
mesh_terms: D004553:Electric Conductivity; D018020:Lithium Compounds / Q000737:chemistry*; D008982:Molybdenum / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D018020:Lithium Compounds; C044659:molybdate; D008982:Molybdenum