Coalescence of Andreev bound states on the surface of a chiral topological semimetal
V. D. Esin, Yu. S. Barash, A. V. Timonina, N. N. Kolesnikov, E. V. Deviatov
Institute of Solid State Physics of the Russian Academy of Sciences, 142432 Chernogolovka, Russia
Abstract
We experimentally investigate the magnetic field dependence of Andreev
transport through a region of proximity-induced
superconductivity in CoSi topological chiral semimetal. With increasing
parallel to the CoSi surface magnetic field,
the sharp subgap peaks, associated with Andreev bound states, move
together to nearly-zero bias position, while there is
only monotonic peaks suppression for normal to the surface fields. The
zero-bias dV/dI resistance value is perfectly
stable with changing the in-plane magnetic field. As the effects are
qualitatively similar for In and Nb superconducting
leads, they reflect the properties of a proximized CoSi surface. The
Andreev states
coalescence and stability of the zero-bias dV/dI value with increasing
in-plane magnetic field are interpreted as the
joined effect of the strong spin-orbit coupling and the Zeeman
interaction, known for proximized semiconductor nanowires. We associate
the observed magnetic field anisotropy with the recently predicted in-plane
polarized spin texture of the Fermi arcs surface states.