  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 the spin-orbit interaction in the graphene layer.
Proximity to heavy p elements is a promising approach; however, their
interaction in graphene heterostructures has not been as intensively studied as
that of ferromagnetic, noble, or heavy d metals, neither as interlayers nor as
substrates. In this study, the effective intercalation of Te atoms in a
graphene on Ir(111) heterostructure is achieved. Combining techniques such as
low energy electron diffraction and scanning tunneling microscopy, the
structural evolution of the system as a function of the Te coverage is
elucidated, uncovering up to two distinct phases. The presented angle-resolved
photoemission spectroscopy analysis reveals the emergence of a bandgap of about
240 meV in the Dirac cone at room temperature, which preserves its
characteristic linear dispersion. Furthermore, a pronounced n-doping effect
induced by Te in the heterostructure is also observed, and remarkably the
possibility of tuning the Dirac point energy towards the Fermi level by
reducing the Te coverage while maintaining the open bandgap is demonstrated.
Spin-resolved measurements unveil a non-planar chiral spin texture with
significant splitting values for both in-plane and out-of-plane spin
components. These experimental findings are consistent with the development of
a quantum spin Hall phase, where a Te-enhanced intrinsic spin orbit coupling in
graphene surpasses the Rashba one and promotes the opening of the spin-orbit
bandgap.
