New type of Weyl semimetal with quadratic double Weyl fermions

• DOI: 10.1073/pnas.1514581113
• Publication Date: 2016-02-02T20:22:15Z
• Authors: Shin-Ming Huang; Su-Yang Xu; Ilya Belopolski; Chi-Cheng Lee; Guoqing Chang; Tay-Rong Chang; BaoKai Wang; Nasser Alidoust; Guang Bian; Madhab Neupane; Daniel Sanchez; Hao Zheng; Horng-Tay Jeng; Arun Bansil; Titus Neupert; Hsin Lin; M. Zahid Hasan
• Keywords: Weyl semimetal; Weyl transformation

We identify a Weyl semimetal state in an inversion breaking, stoichiometric compound strontium silicide, SrSi$_2$, with many new and novel properties that are distinct from the TaAs family. theoretically show SrSi$_2$ is even without spin-orbit coupling that, after inclusion of coupling, two fermions stick together forming exotic double fermion quadratic dispersions higher chiral topological charge 2. Moreover, we find nodes opposite charges located at different energies due to absence mirror symmetry leading unique quantum response external magnetic field can induce dissipationless current. Our systematic results not only much-needed robust candidate but also open door physics possible family materials.