H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
Nat Commun. 2011 Jul 19;2:396. doi: 10.1038/ncomms1406.
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.
当电荷载流子在空间上局限于一维时，传统的费米液体理论就会失效。在这种汤姆松-拉廷格液体中，准粒子被自旋和电荷的独特集体激发所取代，它们以不同的速度独立传播。尽管已经有证据表明存在自旋电荷分离，但还没有一种体相低能探针能够成功区分汤姆松-拉廷格液体和费米液体物理学。在这里，我们通过实验表明，在准一维 Li(0.9)Mo(6)O(17)的金属相中，热霍尔电导率与电霍尔电导率之比随温度的降低而发散，其值比在传统金属中发现的大五个数量级。这一比值的温度依赖性和大小都与汤姆松-拉廷格液体理论一致。在一个体三维固体中如此剧烈的自旋电荷分离表现，为探索当与第二或第三维的耦合恢复时，费米子准粒子图像是如何恢复的，以及需要多长时间来恢复，提供了一个独特的机会。
