Noguchi E.,Tohoku University |
Sugawara K.,Tohoku University |
Yaokawa R.,Toyota Central R AndD Labs. Inc. Nagakute |
Hitosugi T.,Tohoku University |
And 4 more authors.
Advanced Materials | Year: 2015
Results of high-resolution angle-resolved photoemission spectroscopy (ARPES) on tr3-CaSi2 which has the ABC stacking-sequence (tr3) of both Ca and silicene layers along the  crystal axis per unit cell, was reported. In the ARPES-derived band structure, it is observed that the massless Dirac-cone π-electron dispersions at the K(H) point in the Brillouin zone, together with the ω-band dispersions. The Dirac point is located about 2 eV from Fermi level, showing a substantial charge transfer from Ca atoms to silicene layers. The present ARPES results indicate that the sp2 bonding-framework essentially holds in CaSi2 to produce the massless Dirac-cone state at the K point despite the strongly buckled structure in silicene layer.