The TRR 227 kindly invites you to the joint Colloquium of the TRR 227 & FU Physics Department.

Speaker:

Prof. Dr. Matias Bargheer, Institute of Physics and Astronomy, Universität Potsdam & Helmholtz-Zentrum Berlin

Title:

Controlling and calibrating ultrafast energy transfer processes in metal nanostructures for ultrafast spin dynamics and light driven catalysis

Abstract

We investigate energy transfer processes within epitaxial and colloidal metallic nanostructures by quantifying the transport across material interfaces and the local mutual coupling of electrons, spins and phonons within each material. Unconventional forms of energy transport, e.g. heat transport without heating [1] and the dominance of phonon heat transport in the noble metal Au [2] initially observed via Ultrafast X-ray Diffraction (UXRD) [3] are exploited for tailoring the excitation of spin waves in ferromagnetic thin films [4] and the nano-localization of energy in catalytically active Palladium nano-spikes on colloidal gold. We combine the UXRD experiments with ultrafast all-optical methods that are sensitive to the electron and spin systems.

[1] J. Pudell, et al., “Heat transport without heating”, Adv. Funct. Mater. 30, 2004555 (2020).
[2] M. Herzog, et al., “Phonon-dominated energy transport in purely metallic heterostructures”, Adv. Funct. Mater. 32, 2206179 (2022).
[3] M. Mattern, et al.,”Concepts and use cases for picosecond ultrasonics with x-rays”, Photoacoustics 31, 100503 (2023).
[4] J. Jarecki et al., “Controlling effective field contributions to laser-induced magnetization precession by heterostructure design”, Commun. Phys. 7, 12 (2024).