Dirac dispersion generates unusually large Nernst effect in Weyl semimetals

作者：Watzman Sarah J; McCormick Timothy M; Shekhar Chandra; Wu Shu Chun; Sun Yan; Prakash Arati; Felser Claudia; Trivedi Nandini; Heremans Joseph P^*

来源：Physical Review B, 2018, 97(16): 161404.

DOI：10.1103/PhysRevB.97.161404

Weyl semimetals contain linearly dispersing electronic states, offering interesting features in transport yet to be thoroughly explored thermally. Here we show how the Nernst effect, combining entropy with charge transport, gives a unique signature for the presence of Dirac bands and offers a diagnostic to determine if trivial pockets play a role in this transport. The Nernst thermopower of NbP exceeds its conventional thermopower by a 100-fold, and the temperature dependence of the Nernst effect has a pronounced maximum. The charge-neutrality condition dictates that the Fermi level shifts with increasing temperature toward the energy that has the minimum density of states (DOS). In NbP, the agreement of the Nernst and Seebeck data with a model that assumes this minimum DOS resides at the Dirac points is taken as strong experimental evidence that the trivial (non-Dirac) bands play no role in high-temperature transport.

• 出版日期2018-4-18