Regensburg 2007 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 37: Nano structured materials V
MM 37.3: Talk
Thursday, March 29, 2007, 17:15–17:30, H4
Energy transfer via mechanical and thermal channels in metallic nano-objects arrays — •F Banfi1, B Revaz2, C Giannetti2, G Ferrini2, P Vavassori3, V Metlushko4, M Montagnese2, F Cilento2, G Coslovich5, and F Parmigiani5 — 1Department of Condensed Matter Physics, University of Genève, Switzerland — 2Dipartimento di Matematica e Fisica, Università Cattolica, Brescia, Italy — 3Dipartimento di Fisica, Università di Ferrara, Italy — 4Department of Electrical and Computer Engineering, University of Illinois at Chicago, IL — 5Dipartimento di Fisica, Università degli Studi di Trieste, Italy
2D periodic arrays of permalloy nanodisks deposited on Si substrates are investigated with pump probe optical technique. The 150 fs pump beam (λ=800nm, repetition rate 80 MHz) is used as the excitation source, while the relaxation of the sample is measured recording the variation of intensity of the reflected probe beam as a function of the delay between the pump and probe pulses. The reflected intensity of the first-order diffracted beam is measured. The data show 1) a relaxation of the intensity with a time constant τ ∼ ns 2) oscillations dominated by a frequency ω0/2π in the GHz range with a damping rate γ. The energy is transfered from the nanodisk to the Si substrate both via thermal and mechanical energy fluxes, the measured time constant τ setting the timescale for these processes. Numerical simulations suggest that the contribution of the two energy channels to the relaxation time can be disentangle. This technique is therefore suitable to measure the specific heat of mesoscopic samples.