  Incorporating relativistic physics into quantum tunneling can lead to exotic
behavior such as perfect transmission via Klein tunneling. Here, we probe the
tunneling properties of spin-momentum locked relativistic fermions by designing
and implementing a tunneling geometry that utilizes nanowires of the
topological Kondo insulator candidate, SmB6. The nanowires are attached to the
end of scanning tunneling microscope tips, and used to image the bicollinear
stripe spin-order in the antiferromagnet Fe1.03Te with a Neel temperature of
~50 K. The antiferromagnetic stripes become invisible above 10 K concomitant
with the suppression of the topological surface states. We further demonstrate
that the direction of spin-polarization is tied to the tunneling direction. Our
technique establishes SmB6 nanowires as ideal conduits for spin-polarized
currents.
