  We present the characteristics of a simple waveguiding structure constructed
by anisotropic birefringent crystal-metal-chiral medium,
anisotropic-metal-chiral in short, and reveal the chiral-dependent dispersion
and propagation properties of the surface plasmon polaritons (SPPs). We
demonstrate its remarkable discrimination ability to the magnitude and sign of
both the real and imaginary part of the chirality parameter. The anisotropy
plays a key role in such performance and shows tuneable ability in enantiomeric
discrimination even when the chirality parameter is complex-valued. Most
importantly, the physical origin of chiral discrimination stems from the
extrinsic chirality of the system, which arises from the mutual orientation of
the SPPs and the optical axis. Moreover, we also clarify the fundamental
physics behind the chiral discriminating behaviour by associating the intrinsic
quantum spin Hall effect (QSHE) of the SPPs with the electromagnetic field
analysis. This structure does not rely on complicated fabrication but provides
the opportunity of on-chip surface-sensitive biosensing. We anticipate that our
work will stimulate intensive research to investigate the anisotropy-induced
chiral sensing techniques in plasmonic platforms.
