Type-II Dirac semimetals in the YPd2Sn class

Lorentz-invariance-violatingWeyl and Dirac fermions have recently attracted intensive interests as newtypes of particles beyond high-energy physics, and they demonstrate novel physical phenomena such as angle-dependent chiral anomaly and topological Lifshitz transitions. Here, we predict the existence of Lorentz-invariance-violating Dirac fermions in the YPd2Sn class of Heusler alloys that emerge at the boundary between the electronlike and holelike pockets in the Brillouin zone, based on first-principles electronic structure calculations. In combination with the fact that this class of materials was reported to be superconductors, the YPd2Sn class provides an appropriate platform for studying exotic physical properties distinguished from conventional Dirac fermions, especially for realizing possible topological superconductivity.