Photoinduced domain-type collective structural changes with interlayer σ-bonds in the visible region of graphite

We theoretically study the photoinduced domain-type structural changes in the visible region of graphite. By means of the ab initio total-energy calculation, we clarify the adiabatic path for the nucleation of this domain, wherein the interlayer distance of the original graphite is contracted and new interlayer sigma-bonds are induced with a certain periodic buckling pattern. We show that an excitation by few visible photons is energetically enough to trigger the formation of this domain, and this domain is sufficiently stable against the thermal fluctuation at around room temperature. The electronic state of this domain is also shown to have a pseudogap, characteristic to an insulator immersed in the original semimetallic graphite.