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Univ. Paris-Saclay

Sujet de stage / Master 2 Internship

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Ultrafast pure spincurrent transport through antiferromagnets

Contact: VIRET Michel, , michel.viret@cea.fr, +33 1 69 08 71 60
The aim of this internship is to study the ultra-fast spin current propagation through an insulating antiferromagnet.
Possibility of continuation in PhD: Oui
Deadline for application:30/04/2021

Full description:
Pure spin-currents are currently attracting a substantial interest due to their deep implication in future spintronic devices. The booming demand on data consumption pushes new technologies to be able to process bigger volumes of data at a faster rate. Thus, ultrafast manipulation of information processing has now become a challenge of tomorrow’s information technologies. Pure spin currents present several key advantages as they can now be generated, propagated and detected on the sub-picosecond timescale and at nano-sizes. One can therefore envision the possibility of ultrafast spintronic components and the emergence of terahertz spintronic devices.

Several “bricks” are crutial to these devices as spincurrents have to be generated, propagated processed and eventually detected. This project aims at studying the underlying mechanisms of picosecond and sub-picosecond pure spincurrent bursts in antiferromagnetic insulators. The systems under study are composed of three high quality epitaxial layers of nanometric thicknesses, grown by pulsed laser deposition. The first one is the spin injector, i.e. a ferromagnetic layer (La2/3Sr1/3MnO3) which, when subjected to intense femtosecond laser pulses, generates bursts of spin-polarized currents [1]. The second layer is the insulating antiferromagnet NiO, which is the central part of the structure and through which pure spincurrents can propagate [2]. Despite the explanations proposed by several theoretical works [3], the exact nature and characteristics of the spincurrent propopagation remains under debate. Especially, one should tackle the dynamical issue of spincurrents coherently matching the specific antiferromagnetic terahertz resonance.

This is the main objective of this internship project where spin-polarized current will be launched in ultra-fast bursts. Finally, a third Pt layer is used as a detector (via the inverse spin Hall effect mechanism). This trilayer system offers an interesting playground to tackle the opened questions regarding the transport and manipulation of ultrafast spincurrents in insulating antiferromagnets.

During this internship, the student will perform ultrafast time-resolved optical experiments using a femtosecond laser in order to assess the sub-picosecond dynamics of magnetic systems and the propagation of spincurrent bursts. In addition, he/she will also learn how to grow high quality epitaxial samples by pulsed laser deposition. Ideally, the internship will continue in a PhD work.

[1] Kampfrath et al. Nat. Nano. 8 256 (2013) [2] Hahn et al. EPL 108 57005 (2014)
[3] Khymyn et al. Phys. Rev. B 93 224421 (2016)
Technics/methods used during the internship:
Pulsed laser deposition, ultra-fast optical measurements

Tutor of the internship


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