Group Seminar 2024/25

ABSTRACT: Artificial spin ices are two-dimensional lattices built from nanoscale magnetic islands that can take two stable magnetic configurations. The relaxation kinetics of such arrays of Ising-like nanomagnets are governed by thermally-activated switching of the individual magnets, with switching barriers being modified by contact-less magnetostatic coupling to their neighbours.

In the first part of my talk I will discuss results of kinetic Monte Carlo simulations of the demagnetisation in artificial square ice when taking into account distinct rates for clockwise and counter-clockwise switching processes [1]. In particular, even in the absence of disorder, the emergence of coral-shaped magnetic domains can be linked to relatively rare events that "split" the dominant string-like demagnetisation events in the initial stages of relaxation [2].

In the second part of my talk, I will present on how to use thermoplasmonic particles as versatile light-activated nanoscale heaters [3] to promote thermally-activated switching in hybrid magneto-thermoplasmonic metamaterials [4]. In particular, I will present a recent example of an optically reconfigurable nanomagnetic Boolean AND/OR grate with nanosecond operation at picojoule energies that result in a non-volatile output state [5], and discuss other magneto-thermoplasmonic applications that might benefit from light-induced thermal remote control.

[1] N. Leo et al, Chiral switching and dynamic barrier reductions in artificial square ice, New Journal of Physics 23 033024 (2021).
[2] M. Menniti, N. Leo, Pedro Villalba, Matteo Pancaldi, and Paolo Vavassori, in preparation.
[1] G. Baffou, Thermoplasmonics: Heating Metal Nanoparticles Using Light, Cambridge University Press (2017).
[2] M. Pancaldi, N. Leo, and P. Vavassori, Selective and Fast Plasmon-Assisted Photo-Heating of Nanomagnets, Nanoscale 11, 7656 (2019).
[3] P. Gypens, N. Leo, M. Menniti, P. Vavassori, and J. Laliaert, Thermoplasmonic nanomagnetic logic gates, Phys. Rev. Appl. 18, 024014 (2022).