07 Avril 2022

Séminaire Axes 4 et 5 présenté par Lucile SOUMAH

"Nanometer thick films of Bismuth doped Yttrium Iron garnet and their applications."


Ultrafast dynamics and condensed matter group
Stockholm University
10691 Stockholm

à l’auditorium et par zoom :

ID de réunion : 890 5384 6047
Code secret : mjMR0W

Résumé :

Magnetic insulators are materials of choice when it comes to spin dynamics. Compared to their conducting counterparts they exhibit very low magnetic losses which enables long distance spin wave propagation. Moreover, when combined with a heavy metal top layer, the spin dynamics in those insulators can be converted and detected via a DC current in the metallic layer. Generation of spin dynamics using DC current in heavy metal// magnetic insulators films can also be achieved but remains more challenging as it requires magnetic insulators with low magnetic damping and low thickness.  The first observation of those DC -current induced magnetic oscillation was performed in nanometer thick Yttrium Iron Garnet (YIG) films grown by pulsed laser deposition [1]. The easy in plane magnetic axis in those thin films, imposed by the shape anisotropy (unavoidable for thin films) and the low spin orbit coupling, appeared to bring some limitations in terms of applications for the magnon spintronic community. Therefore, out of plane magnetised ultrathin magnetic insulators with low magnetic losses remained, for a while, a missing brick, and a need for magnon-spintronic applications. Moreover, light-based detection techniques, commonly used to image spin dynamics in insulators (Brillouin Light scattering), were suffering of the low magneto-optical coefficient in those in-plane magnetised YIG films which made the detection long and tedious.

We present in this seminar the growth of nanometer thick, Bismuth doped YIG films by pulsed laser deposition technique with high faraday rotation, perpendicular magnetic anisotropy, and magnetic losses comparable to the undoped YIG thin films [2]. We will show how this new material has been proven to be attractive for the field of magnons spintronics [3] and light induced magnetization dynamics [4].

[1] Collet, Martin, et al. « Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin–orbit torque. » Nature communications 7.1 (2016): 1-8.

[2] Soumah, Lucile, et al. « Ultra-low damping insulating magnetic thin films get perpendicular. » Nature communications 9.1 (2018): 1-6.

[3] Evelt, M., et al. « Emission of coherent propagating magnons by insulator-based spin-orbit-torque oscillators. » Physical Review Applied 10.4 (2018): 041002

[4] Soumah, Lucile, et al. « Optical Frequency Up-Conversion of the Ferromagnetic Resonance in an Ultrathin Garnet Mediated by Magnetoelastic Coupling. » Physical Review Letters 127.7 (2021): 077203

07 Avril 2022, 11h0012h00
Auditorium de l'IPCMS et par Zoom