Type-III Weyl semimetals: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>TaSe</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">I</mml:mi></mml:mrow></mml:math>

Abstract

The Fermi surface plays a crucial rule in understanding the fundamental physics of crystals, such as superconductivity, the charge/spin density wave, and anomalous transport. Here, the authors discover the type-III Weyl semimetal, whose novel Fermi surface consists of two electron or hole pockets touching at the double Weyl points in Ta${}_{2}$Se${}_{8}$I, supporting the axionic charge density wave phase at low temperature. A unified and transparent picture to classify all of type-I, type-II, and type-III Weyl fermions based on the general tilting mechanism is also found.

Topics & Concepts