  Engineering and enhancing inversion symmetry breaking in solids is a major
goal in condensed matter physics and materials science, as a route to advancing
new physics and applications ranging from improved ferroelectrics for memory
devices to materials hosting Majorana zero modes for quantum computing. Here,
we uncover a new mechanism for realising a much larger energy scale of
inversion symmetry breaking at surfaces and interfaces than is typically
achieved. The key ingredient is a pronounced asymmetry of surface hopping
energies, i.e. a kinetic energy-driven inversion symmetry breaking, whose
energy scale is pinned at a significant fraction of the bandwidth. We show,
from spin- and angle-resolved photoemission, how this enables surface states of
3d and 4d-based transition-metal oxides to surprisingly develop some of the
largest Rashba-like spin splittings that are known. Our findings open new
possibilities to produce spin textured states in oxides which exploit the full
potential of the bare atomic spin-orbit coupling, raising exciting prospects
for oxide spintronics. More generally, the core structural building blocks
which enable this are common to numerous materials, providing the prospect of
enhanced inversion symmetry breaking at judiciously-chosen surfaces of a
plethora of compounds, and suggesting routes to interfacial control of
inversion symmetry breaking in designer heterostructures.
