Engineering a Spin-Orbit Bandgap in Graphene-Tellurium Heterostructures

Intensive research has focused on harnessing the potential of graphene for electronic, optoelectronic, and spintronic devices by generating a bandgap at the Dirac point and enhancing spin-orbit interaction. While proximity to heavy p elements is promising, their interaction in graphene heterostructures remains underexplored compared to ferromagnetic, noble, or heavy metals. This study demonstrates the effective intercalation of Te atoms in a graphene/Ir(111) heterostructure. Using low-energy electron diffraction and scanning tunneling microscopy, two distinct structural phases are identified as a function of Te coverage. Angle-resolved photoemission spectroscopy reveals a 240 meV bandgap at the Dirac cone at room temperature, preserving linear dispersion, along with a pronounced n-doping effect confirmed by quasiparticle interference maps. Notably, reducing Te coverage tunes the Dirac point toward the Fermi level while maintaining the bandgap. Spin-resolved measurements uncover a non-planar chiral spin texture with significant splitting in both in-plane and out-of-plane components, as well as evidence of an emerging edge state from scanning tunneling spectroscopy. These findings highlight Te-enhanced intrinsic spin-orbit coupling in graphene, surpassing the extrinsic Rashba effect and promoting a spin-orbit-induced bandgap. This system offers a promising platform for spin-dependent transport phenomena, such as the quantum spin Hall effect.