  In recent years, substantial progress has been made regarding the application
of quasiclassical theory on superconducting hybrid structures. This theoretical
framework is reliant on a proper set of boundary conditions in order to
describe multilayered systems. With the advent of the field of superconducting
spintronics, systems which combine heavy metal layers, in which there is large
spin--orbit coupling, with ferromagnets have received a great deal of
attention, due to their potential for generating long range triplet
superconductivity. In contrast to interfaces of strongly spin polarized
materials, which are well understood, a quasiclassical theory for interfaces in
systems where there is significant spin--orbit coupling does not yet exist.
After reviewing the quasiclassical theory for interfaces, we here solve this
problem by deriving a new set of boundary conditions which take spin--orbit
coupling explicitly into account. We then go on to apply these boundary
conditions to a superconductor-ferromagnet (SF) bilayer and an SFS Josephson
weak link, demonstrating the emergence of long range triplet superconductivity
in these systems.
