The long march to silicene and germanene

At the origin of all artificial graphene-like two-dimensional mono-elemental materials, coined Xenes, is the seminal, totally iconoclastic, paper of Takeda and Shiraishi, who predicted already in 1994 the ‘Theoretical possibility of stage corrugation in Si and Ge analogs of graphite’, in other words, the possible existence of freestanding silicene and germanene in a so-called low-buckled honeycomb geometry, at variance with graphene, which is nominally flat. Silicene was synthesized and presented for the first time at the 2011 APS March meeting in Dallas. After a gold rush, germanene, the second xene, was obtained in 2014, exactly ten years after the advent of graphene. Then a cornucopia of other xenes from borophene to tellurene appeared in succession. Yet, a signature of germanene was already encrypted in a 1971 thesis, but it remained undeciphered and unpublished for more than half a century. Here, the saga of of silicene and germanene, from the dark ages to the limelight will be narrated.