  In topological semimetals, nodes appear at symmetry points in the Brillouin
zone as a result of band inversion, and yield quasi-relativistic massless
fermions at low energies. Cd3As2 is a three-dimensional topological semimetal
that hosts two Dirac cones responsible for a variety of quantum phenomena. In
this work, we demonstrate the strain tuning of the Dirac nodes of Cd3As2
through a combination of magnetooptical infrared spectroscopy and
high-resolution X-ray diffraction studies performed on epitaxial films. In
these thin films, we observe a giant enhancement of the node separation in
momentum space by close to a factor of 4. A combination of experimental
measurements and theoretical modelling allows relate the origin of this
enhancement to a strengthening of the topological band inversion driven by
lattice strain. Our results demonstrate how strain can be used as a knob to
tune the topological properties of semimetals and to potentially enhance their
performance and response for various applications.
