Nonequilibrium Magneto-Conductance as a Manifestation of Spin Filtering in Chiral Nanojunctions

It is generally accepted
that spin-dependent electron
transmission
may appear in chiral systems, even without magnetic components, as
long as significant spin–orbit coupling is present in some
of its elements. However, how this chirality-induced spin selectivity
(CISS) manifests in experiments, where the system is taken out of
equilibrium, is still debated. Aided by group theoretical considerations
and nonequilibrium DFT-based quantum transport calculations, here
we show that when spatial symmetries that forbid a finite spin polarization
in equilibrium are broken, a net spin accumulation
appears at finite bias in an arbitrary two-terminal nanojunction.
Furthermore, when a suitably magnetized detector is introduced into
the system, the net spin accumulation, in turn, translates into a
finite magneto-conductance. The symmetry prerequisites are mostly
analogous to those for the spin polarization at any bias with the
vectorial nature given by the direction of magnetization, hence establishing
an interconnection between these quantities.