  We have studied spin-orbit (SO) field in Ni$_{80}$Fe$_{20}$(Py)/W/Pt trilayer
by means of spin-torque ferromagnetic resonance, and demonstrated that the W/Pt
interface generates an extra SO field acting on the Py layer. This
unprecedented field originates from the following three processes, 1) spin
accumulation at W/Pt interface via the Rashba-Edelstein effect, 2) diffusive
spin transport in the W layer, and 3) spin absorption into the Py layer through
accumulation at the Py/W interface. Our result means that we can create extra
SO field away from the ferromagnet/ metal interface and control its strength by
a combination of two different metals.
