Despite its low atomic number and inversion symmetry, recent electronic measurements demonstrate that (group-IV) graphene has a greatly disappointing spin lifetime, corroborated by theory showing strong spin-flip scattering by flexural (out-of-plane) phonons. There exists a class of graphene-like 2-dimensional semiconductors formed from elemental group-IV OR group V atoms, some of which may be immune to this deleterious coupling. Only one is known to mechanically exfoliate like graphene: phosphorene (monolayer black phosphorus). We analyzed the symmetry of its electronic bandstructure including spin-orbit interaction close to the insulating gap edge with special interest in the spin-transport properties. Importantly, we discovered that the natural buckling of the honeycomb crystal lattice results in anisotropic spin flip processes that are entirely decoupled from flexural phonons for a particular in-plane spin orientation. This discovery allows us to predict a spin lifetime comparable to bulk Si, vastly greater than graphene.
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Researchers should cite this work as follows:
Pengke Li and Ian Appelbaum, Electrons and holes in phosphorene, Phys. Rev. B 90, 115439 (2014)
203 Physics, Purdue University, West Lafayette, IN