SPICE Workshop on Nanomagnetism in 3D, April 30th - May 2nd 2024
Gianluca Gubbiotti
Magnonics, the research field that uses spin waves (SWs), the collective excitations of ordered magnetic materials, as a tool for signal processing, communication, and computation have rapidly grown during the last decade due to the low-energy-consumption property.[1] Magnonics systems investigated up to now are mainly planar systems that can be patterned out of an extended layer that is deposited on a flat substrate. The interest in 3D magnonic nanostructures follows the latest trend in CMOS electronics based on the expansion from 2D planar to 3D vertically integrated structures.[3]
3D magnonic systems might offer several advantages over 2D systems allowing for a large number of vertical connections between the layers thus increasing the density of elements for the fabrication of scalable and configurable magnonics.
In this talk, I will review the different strategies to build the next generation of magnonic systems. The first of them is an extension of planar patterned nanostructures, where arrays of patterned magnetic dots or antidots have a layered structure. In this case, the vertical stacking of ferromagnetic materials, placed in direct contact or separated by a non-magnetic spacer, adds new functionalities and degrees of freedom for controlling the SW band structure. An alternative approach to physical patterning is based on the use of hybrid heterostructures in the form of bilayer systems including metal-insulator, metal-heavy metal, metal-antiferromagnet, and metal-ferroelectric, where new properties of SWs such as confining and filtering, guiding and steering, non-reciprocity and reconfigurability in the magnonic band structure, emerge from the interaction between the continuous magnetic film, where spin waves propagate, and the vertical magnetic/nonmagnetic layers which induce periodic modulation of either the static or the dynamic internal magnetic field of the magnetic film itself.[4-6] 3D magnonic systems in the form of meander-shaped ferromagnetic films fabricated on top of pre-patterned substrates have been also proposed as prototypes for the transmission of SW signals in 3D magnonic networks.[7] Finally, the recent observation of SW moiré edge and cavity modes in twisted magnetic lattices will be reviewed.[8]
G.G. acknowledges petaspin association (www.petaspin.com) for the support.
[1] A. Barman et al 2021 J. Phys.: Condens. Matter 33 413001. [2] Gubbiotti G (ed) 2019 Three Dimensional Magnonics: Layered Micro-and Nanostructures (Jenny Stanford Publishing). [3] P. Graczyk et al, Phys. Rev. B 98, p. 174420, Nov. 2018. [4] K. Szulc et al, Phys. Rev. Appl. 14 034063 (2020) [5] J. Chen et al, Phys. Rev. B 100, 104427 (2019); J. Chen et al, ACS Nano 15, 9076 (2021) [6] S. Hamalainen et al, Nat. Commun. 9 4853 (2018) [7] G. Gubbiotti et al, PRApplied 15, 014061 (2021). [8] H. Wang et al., Phys. Rev. X 13, 021016 (2023)