The Fe-projected vibrational density of states $g\left(E\right)$ in nanoscale ${}^{57}\text{F}\text{e}/M$ multilayers, where $M=\text{Cr}$, Co, Cu, Pd, or Ag was measured by nuclear resonant inelastic x-ray scattering. With decreasing Fe thickness, the high-energy phonon peak of Fe near 36 meV is suppressed for the “soft” metals Ag, Pd, and Cu, but much less so for the “hard” metals Co and Cr. This effect is attributed to Fe phonon confinement and interface localization due to an energy mismatch between $g\left(E\right)$ of $M$ and of Fe.

• Received 7 March 2008

DOI:https://doi.org/10.1103/PhysRevB.77.165410