  Novel fermions with a pseudospin-1 structure can be realized as emergent
quasiparticles in condensed matter systems. Here, we investigate its unusual
properties during the Andreev reflection at a normal-metal/superconductor (NS)
interface. We show that distinct from the previously studied pseudospin-1/2 and
two dimensional electron gas models, the pseudospin-1 fermions exhibit a
strongly enhanced Andreev reflection probability, and remarkably, can be
further tuned to approach perfect Andreev reflection with unit efficiency for
all incident angles, exhibiting a previously unknown {super-Andreev reflection
effect}. The super-Andreev reflection leads to perfect transparency of the NS
interface that strongly promotes charge injection into the superconductor, and
directly manifests as a differential conductance peak which can be readily
probed in experiment. Additionally, we find that sizable longitudinal shifts
exist in the normal and Andreev reflections of pseudospin-1 fermions. Distinct
from the pseudospin-1/2 case, the shift is always in the forward direction in
the subgap regime, regardless of whether the reflection is of retro- or
specular type.

Mesoscale and Nanoscale Physics