Observation of highly anisotropic bulk dispersion and spin-polarized topological surface states in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CoTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>
Atasi Chakraborty, Jun Fujii, Chia‐Nung Kuo, C. S. Lue, Antonio Politano, I. Vobornik, Amit Agarwal
Abstract
We present ${\mathrm{CoTe}}_{2}$ as a type-II Dirac semimetal supporting Lorentz-symmetry violating Dirac fermions in the vicinity of the Fermi energy. By combining first-principles ab initio calculations with experimental angle-resolved photoemission spectroscopy results, we show ${\mathrm{CoTe}}_{2}$ hosts a pair of type-II Dirac fermions around 90 meV above the Fermi energy. In addition to the bulk Dirac fermions, we find several topological band inversions in bulk ${\mathrm{CoTe}}_{2}$, which gives rise to a ladder of spin-polarized surface states over a wide range of energies. In contrast to the surface states which typically display Rashba-type in-plane spin splitting, we find that ${\mathrm{CoTe}}_{2}$ hosts interesting out-of-plane spin polarization as well. Our work establishes ${\mathrm{CoTe}}_{2}$ as a potential candidate for the exploration of Dirac fermiology and applications in spintronic devices, infrared plasmonics, and ultrafast optoelectronics.