  Spin waves can transport both energy and angular momentum over long distances
as they propagate. However, due to damping, their amplitude decreases
exponentially as they move away from the source, leaving little capability for
manipulating how much energy and angular momentum is to be delivered where.
Here we show that a suitable local reduction of the effective field can lead to
a large accumulation of spin wave energy far from the source. Moreover, both
the location and the amount of energy to be delivered can be controlled
accurately with geometry and externalm magnetic fields. Thus, we put forward a
general, robust and flexible approach to convey both heat and spin in
ferromagnets, which can be directly used in spintronic devices.
