  The interaction between the itinerant spins in metals and localized spins in
magnetic insulators thus far has only been explored in collinear spin systems,
such as garnets. Here, we report the spin-Hall magnetoresistance (SMR)
sensitive to the surface magnetization of the spin-spiral material, Cu_2OSeO_3.
We experimentally demonstrate that the angular dependence of the SMR changes
drastically at the transition between the helical spiral and the conical spiral
phases. Furthermore, the sign and magnitude of the SMR in the conical spiral
state are controlled by the cone angle. We show that this complex behaviour can
be qualitatively explained within the SMR theory initially developed for
collinear magnets. In addition, we studied the spin Seebeck effect (SSE), which
is sensitive to the bulk magnetization. It originates from the conversion of
thermally excited low-energy spin waves in the magnet, known as magnons, into
the spin current in the adjacent metal contact (Pt). The SSE displays
unconventional behavior where not only the magnitude but also the phase of the
SSE vary with the applied magnetic field.
