  Magnon bands are known to exhibit nontrivial topology in ordered magnets
under suitable conditions, engendering topological phases referred to as
magnonic topological insulators. Conventional methods to drive a magnonic
topological phase transition are bulk magnetic or thermal operations such as
changing the direction of an external magnetic field or varying the temperature
of the system, which are undesired in device applications of magnon topology.
In this work, we lift the limitation of the magnon topology control on the bulk
non-electronic manipulation by proposing a scheme to manipulate magnonic
topological phases by electronic boundary operations of spin chirality
injection. More specifically, we consider a ferromagnetic honeycomb lattice and
show that a finite spin chirality injected from the boundary of the system via
the spin Hall effects introduces a tunable sublattice-symmetry-breaking mass
term to the bosonic counterpart of the Haldane model for the Chern insulators
and thereby allows us to electronically manipulate the bulk topology of magnons
from the boundary. The "shoulder" in the thermal Hall conductivity profile is
proposed as an experimental probe of the chirality-induced topological phase
transition. The scheme for the boundary manipulation of the magnon topology is
shown to work for a honeycomb antiferromagnet as well. We envisage that the
interfacial chirality injection may offer a nonintrusive electronic means to
tune the static and the dynamical bulk properties of general magnetic systems.
