Quantum spin Hall effect on germanene nanorod embedded in completely hydrogenated germanene

We show that germanene nanoroads embedded in completely hydrogenated germanene (germanane) exhibits a quantum spin Hall effect (QSHE). These nanoroads can be obtained experimentally by local hydrogen dissociation from germanane. Using first-principle calculations we predict that germanene nanoroads with zigzag interfaces show dissipationless conducting channels with in-plane and out-of-plane spin textures.