Abstract
-
Topological insulators are a new class of material1,2
, that exhibit
robust gapless surface states protected by time-reversal
symmetry3,4
. The interplay of such symmetry-protected
topological surface states and symmetry-broken states (for
example, superconductivity) provides a platform for exploring
new quantum phenomena and functionalities, such as
one-dimensional chiral or helical gapless Majorana fermions5
,
and Majorana zero modes6
that may find application in faulttolerant
quantum computation7,8
. Inducing superconductivity
on the topological surface states is a prerequisite for their
experimental realization1,2
. Here, by growing high-quality
topological insulator Bi2Se3 films on a d-wave superconductor
Bi2Sr2CaCu2O8+δ using molecular beam epitaxy, we are
able to induce high-temperature superconductivity on the
surface states of Bi2Se3 films with a large pairing gap up
to 15 meV. Interestingly, distinct from the d-wave pairing of
Bi2Sr2CaCu2O8+δ
, the proximity-induced gap on the surface
states is nearly isotropic and consistent with predominant
s-wave pairing as revealed by angle-resolved photoemission
spectroscopy. Our work could provide a critical step towards
the realization of the long sought Majorana zero modes