Anomalous temperature dependence of phonon pumping by ferromagnetic resonance in Co/Pd multilayers with perpendicular anisotropy

Abstract

We demonstrate the pumping of phonons by ferromagnetic resonance in a series of [Co(0.8 nm)/Pd(1.5 nm)]${}_n$ multilayers ($n=$ 6, 11, 15, and 20) with large magnetostriction and perpendicular magnetic anisotropy. The effect is shown using broadband ferromagnetic resonance over a range of temperatures (10 to 300 K), where a resonant damping enhancement is observed at frequencies corresponding to standing wave phonons across the multilayer. The strength of this effect is enhanced by approximately a factor of 4 at 10 K compared to room temperature, which is anomalous in the sense that the temperature dependence of the magnetostriction predicts an enhancement that is less than a factor of 2. Lastly, we demonstrate that the damping enhancement is correlated with a shift in the ferromagnetic resonance field as predicted quantitatively from linear response theory.

10 pages, 11 figures

References in corpus (2)

• Dynamic Magnetoelastic Boundary Conditions and the Pumping of Phonons
• Magnetoelastic Gilbert damping in magnetostrictive Fe${}_{0.7}$Ga${}_{0.3}$ thin films

Cited by in corpus (1)

• Chiral phonons and phononic birefringence in ferromagnetic metal - bulk acoustic resonator hybrids