  Spin-to-heat current conversion effects have been investigated in bilayer
films consisting of a paramagnetic metal (PM; Pt, W, or Ta) and a ferromagnetic
metal (FM; CoFeB or permalloy). When a charge current is applied to the PM/FM
bilayer film, a spin current is generated across the PM/FM interface owing to
the spin Hall effect in PM. The spin current was found to exhibit cooling and
heating features depending on the sign of the spin Hall angle of PM, where the
spin-current-induced contribution is estimated by subtracting the contribution
of the anomalous Ettingshausen effect in FM monolayer films. We also found that
the magnitude of the spin-current-induced temperature modulation in the
Pt/CoFeB film is greater than but comparable to that in the Pt/permalloy film,
although the spin dependence of the Peltier coefficient for CoFeB is expected
to be greater than that for permalloy. We discuss the origin of the observed
behaviors with the aid of model calculations; the signals in the PM/FM films
may contain the contributions not only from the electron-driven spin-dependent
Peltier effect but also from the magnon-driven spin Peltier effect.
