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Séminaire Magnétisme et Physique du spin de l’INSP

Nanomagnonics with engineered reconfigurable spin-textures - Daniela Petti - Jeudi 11 avril 2019 à 11 h

INSP - Sorbonne Université - 4 place Jussieu - 75005 Paris - Barre 22-32, 2e étage, salle 201

Daniela Petti - Institut Polytechnique de Milan

Abstract

Magnonics, which relies on the use of spin-waves for information processing, holds promises as an emerging technology for highly efficient computing platforms. In this context, in the last years, many concepts for analog computing have been proposed. However, controlling spin-waves at the nanoscale, which is crucial for the realization of magnonic nanodevices, is extremely challenging due to the difficulty in controlling the nanoscopic magnetic properties via conventional nanofabrication techniques. We recently demonstrated a new technique, thermally assisted magnetic Scanning Probe Lithography, tam-SPL, for creating reconfigurable magnonic structures by performing a highly localized field cooling with the hot tip of a scanning probe microscope, in an exchange bias bilayer [1]. By controlling the patterning geometry and the external magnetic field direction, we demonstrate a strategy for stabilizing complex multidimensional spin-textures ranging from 2D domains with tailored spin-configuration, to straight and curved 1D magnetic domain walls, to 0D tailored topological solitons such as vortices and Bloch lines with deterministically controlled chirality, position and vorticity [2]. In such structures, by micro-Brillouin Light Scattering and by space and time-resolved scanning transmission X-ray microscopy imaging, we provide direct evidence for the controlled excitation, channelling and steering of propagating spin-waves with no need of external fields [1,3]. In particular, we experimentally demonstrate straight and curved nanomagnonic waveguides based on domain walls and a prototypic nanomagnonic circuit based on two converging waveguides, allowing for the tunable spatial superposition and interaction of confined spin-waves modes. [3] Finally, in an exchange biased synthetic antiferromagnet (SAF), we use magnonic nanoantennas based on tailored spin-textures for launching spatially shaped coherent wavefronts, diffraction-limited spin-wave beams, and generating robust multi-beam interference patterns, which spatially extend for several times the spin-wave wavelength. Furthermore, we show that intriguing features such as one-way propagation naturally arise from the spin-wave non-reciprocity, preserving the high quality of the interference patterns from spurious counterpropagating modes [4]. The ability to control magnons via nanoscale-designed spin-textures opens up a plethora of exciting possibilities for the realization of energy-efficient computing platforms.

[1] E. Albisetti, D. Petti et al., Nature Nanotechnology, 11 545–551 (2016).
[2] E. Albisetti, A. Calò, .., D. Petti, Applied Physics Letters, 113 162401 (2018).
[3] E. Albisetti, D. Petti et al., Communications Physics 1, 56 (2018).
[4] E. Albisetti, S. Tacchi, .., D. Petti, submitte