ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarUnai AtxitiaInstitute of Materials Science, Madrid (host: Rózsa 
Levente)On the conditions for femtosecond laser-induced ultrafast toggle 
switching in 2D ferrimagnetic alloys Tuesday, 17 September 2024, 10:00, KFKI 
Campus, Bldg. 1, 2nd floor, Conference RoomThe Mermin-Wagner theorem 
establishes that long-range magnetic order is prohibited in two-dimensional 
(2D) isotropic magnets with short-range interactions due to the effects of 
thermal fluctuations. Nevertheless, magnetically stable 2D van der Waals 
(vdW) materials have recently been discovered, where magnetic anisotropy 
plays a crucial role in stabilizing magnetic order [1]. These materials offer 
the opportunity to explore fundamental questions that remain unanswered [2]. 
A prominent example is field-free, all-optical ultrafast magnetization 
switching, which has been experimentally demonstrated in 3D ferrimagnetic 
GdFe alloys. Despite recent efforts to understand the mechanisms underlying 
this effect in bulk 3D ferrimagnetic alloys [3], the implications of 
dimensional effects in 2D systems remain undetermined.In this study, we 
explore the impact of reduced dimensionality on the ultrafast magnetization 
switching effect in 2D ferrimagnets using atomistic spin dynamics (ASD) 
simulations. ASD techniques account for thermal fluctuations, which 
significantly influence the magnetic behavior of 2D materials [4]. Through 
this approach, we aim to understand how magnetic anisotropy affects the 
switching phenomenon in 2D structures compared to bulk systems.Firstly, our 
results show that while the critical temperature in 3D systems linearly 
depends on the anisotropy value, this dependence is logarithmic in 2D 
structures. Secondly, we find that the temperature dependence of the magnetic 
order relaxation time, following a sudden temperature increase, shows only a 
slight dependence on anisotropy in 3D systems. In contrast, the behavior in 
2D systems as a function of anisotropy is much more complex. Finally, we 
demonstrate that femtosecond laser pulse-induced toggle switching in 2D 
ferrimagnets is possible. However, unlike in 3D systems, where the anisotropy 
value has little effect on the switching process, in 2D systems, switching is 
only possible at relatively high anisotropy values.Our findings pave the way 
for understanding the influence of dimensionality on the fundamental 
mechanisms of laser-induced ultrafast toggle switching. Furthermore, our 
results encourage the search for novel 2D ferrimagnetic materials with 
increased magnetic anisotropy, making them potential candidates to exhibit 
this effect.[1] M. Gibertini, M. Koperski, A.F. Morpurgo, et al., Nat. 
Nanotechnol. 14, 408 (2019). [2] S. Jenkins et al. Nat. Comm. 13, 6917 
(2022)[3] F. Jakobs and U. Atxitia. Phys. Rev. B 106, 134414 (2022). [4] Q. 
H. Wang, A. Bedoya-Pinto, M. Blei, et al., ACS Nano 16, 6960 
(2022). Minden érdeklődőt szívesen látunk! - Everyone is welcome to 
attend.Attila Nagysem-admin AT szfki.hu