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Theme 3 colloquium by Dr. Davide Bossini: 'Ultrafast amplification and non-linear magneto-elastic coupling of coherent magnon modes in an antiferromagnet' (Lecture)

Tuesday 16 February 2021Add to my calendar
from 16:00
dr. Davide Bossini (Dept. of Physics and Center for Applied Photonics, University of Konstanz, Germany)

Antiferromagnets have recently surged as candidates for a novel paradigm of spintronics devices able to outperform ferro- and ferrimagnetic materials in terms of operational frequency, storage density and resilience to external fields. The quest for pushing the fundamental boundaries of the manipulation of the macroscopic properties of antiferromagnets motivates the use of ultrashort light pulses as stimulus to drive (sub)-picosecond spin dynamics. Two major aspects concerning the ultrafast spin dynamics have been hitherto barely addressed, namely the possibility of a spin-charges coupling, especially in a coherent regime, and the role played by domain walls. Intrinsically the long-range antiferromagnetic order presents domains, which can hardly be manipulated. This magnetic texture and the magneto-elastic coupling - which is intimately interconnected to the domain structure - have been very recently shown to play a major role in the mechanism allowing electric manipulations of the Néel vector. In my talk I will present several strategies to investigate the coupling between charges and spins on the ultrafast time scale. In particular, I will discuss how a joint electronic and magnonic excitation results in triggering a magnetic phase transition and in the generation and controlled amplification of coherent magnons in the THz regime. In the latter case, the analysis of the subsequent spin dynamics reveals an unexpected coupling between two different magnon modes. This phenomenon is interpreted in terms of the contribution of the domain walls to the spin dynamics, by means of a magneto-elastic interaction. Employing this concept with samples properly engineered may result in a coherent energy transfer between propagating magnon modes, in the absence of Joule heating.

prof. Theo Rasing, prof. Alexey Kimel, and sr. Johan Mentink