Type-II Dirac semimetals in the YPd$_2$Sn class

TL;DR

This paper predicts Lorentz-invariance-violating Dirac fermions in YPd$_2$Sn Heusler alloys, which could serve as a platform for exploring exotic topological superconductivity and novel physical phenomena.

Contribution

It introduces the first-principles prediction of Lorentz-violating Dirac fermions in YPd$_2$Sn alloys, linking topological properties with superconductivity.

Findings

Existence of Lorentz-invariance-violating Dirac fermions at the boundary of electron and hole pockets.

YPd$_2$Sn alloys are superconducting, providing a platform for studying topological superconductivity.

Potential for realizing exotic physical phenomena beyond conventional Dirac fermions.

Abstract

The Lorentz-invariance-violating Weyl and Dirac fermions have recently attracted intensive interests as new types of particles beyond high-energy physics, and they demonstrate novel physical phenomena such as angle-dependent chiral anomaly and topological Lifshitz transition. Here we predict the existence of Lorentz-invariance-violating Dirac fermions in the YPd$_2$Sn class of Heusler alloys that emerge at the boundary between the electron-like and hole-like pockets in the Brillouin zone, based on the first-principles electronic structure calculations. In combination with the fact that this class of materials was all reported to be superconductors, the YPd$_2$Sn class provides an appropriate platform for studying exotic physical properties distinguished from conventional Dirac fermions, especially for realizing possible topological superconductivity.