  Two-dimensional (2D) Dirac materials have attracted intense research efforts
due to their promise for applications ranging from field-effect transistors and
low-power electronics to fault-tolerant quantum computation. One key challenge
is to fabricate 2D Dirac materials hosting Dirac electrons. Here, monolayer
germanene is successfully fabricated on a Ag2Ge surface alloy. Scanning
tunneling spectroscopy measurements revealed a linear energy dispersion
relation. The latter was supported by density functional theory calculations.
These results demonstrate that monolayer germanene can be realistically
fabricated on a Ag2Ge surface alloy. The finding opens the door to exploration
and study of 2D Dirac material physics and device applications.
