  State-of-the-art topological devices require the use topological surface
states to drive electronic transport. In this study, we examine a tunable
topological system, $Ge(Bi_{x}Sb_{1-x})_{2}Te_{4}$, for a range of 'x' values
from 0 to 1, using a combination of Fourier Transform Scanning Tunneling
Spectroscopy (FT-STS) and Angle-Resolved Photoemission Spectroscopy (ARPES).
Our results show that the Dirac point shifts linearly with 'x', crossing the
Fermi energy near x = 0.7. This novel observation of a smoothly tunable,
isolated Dirac point crossing through the topological transport regime and
having strong linear dependence with substitution can be critical for future
topological spintronics applications.
