Nernst effect and dimensionality in the quantum limit

• Published in: Nature physics Vol. 6; no. 1; pp. 26 - 29
• Main Authors: Zhu, Zengwei, Yang, Huan, Fauqué, Benoît, Kopelevich, Yakov, Behnia, Kamran
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2010; Nature Publishing Group
• Subjects: Atomic; Carbon; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Electrons; letter; Mathematical and Computational Physics; Molecular; Nanostructured materials; Optical and Plasma Physics; Physics; Physics and Astronomy; Quantum physics; Theoretical; Theory; Topology
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys1437

The Nernst effect—the generation of a transverse electric field in a system subject to a longitudinal temperature gradient and perpendicular magnetic field—is increasingly used as a probe of a material’s electronic structure. The discovery of an unexpected Nernst response in graphite establishes the role of dimensionality on this effect, and enables the individual contributions of bulk and surface to be distinguished. The Nernst effect has recently emerged as a very sensitive, yet poorly understood, probe of electron organization in solids 1 , 2 , 3 , 4 . Graphene, a single layer of carbon atoms set in a honeycomb lattice, embeds a two-dimensional gas of massless electrons 5 and hosts a particular version of the quantum Hall effect 6 , 7 . Recent experimental investigations of its thermoelectric response 8 , 9 , 10 are in agreement with the theory conceived for a two-dimensional electron system in the quantum Hall regime 11 , 12 . Here, we report on a study of graphite 13 , a macroscopic stack of graphene layers, which establishes a fundamental link between the dimensionality of an electronic system and its Nernst response. In striking contrast with the single-layer case, the Nernst signal sharply peaks whenever a Landau level meets the Fermi level. Thus, the degrees of freedom provided by finite interlayer coupling lead to an enhanced thermoelectric response in the vicinity of the quantum limit. As Landau quantization slices a three-dimensional Fermi surface, each intersection of a Landau level with the Fermi level modifies the Fermi-surface topology. According to our results, the most prominent signature of such a topological phase transition emerges in the transverse thermoelectric response.