D emagnetization with an HHG Source may 30 2017 Katherine Légaré 64 bytes 8 796 093 022 208 bytes 8 T B Studying Ultrafast O ptical D emagnetization Motivation Ultrafast ID: 797723
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Slide1
Probing
Ultrafast Optical Demagnetization with an HHG Source
may 30, 2017
Katherine Légaré
Slide264 bytes
8 796 093 022 208 bytes(8 TB)
Studying Ultrafast Optical DemagnetizationMotivation
Slide3Ultrafast
Optical DemagnetizationDiscoveryArticle by Beaurepaire et al. in Physical Review Letters, 1996.
Slide4Spin system
Lattice
Laser pulse
Electronic
system
Ultrafast
Optical
D
emagnetization
Three temperature model
Pfau
, B
et
al.
Nat
.
Commun
.
3
(2012).
Surrounding
material
Slide5Magnetization
Amplitude Probing TechniqueMOKE (Magneto-Optic Kerr Effect)Technique used by Beaurepaire et al.Reflectivity measurementNear infrared pump and probe
M
External magnetic field
Slide6Magnetization
Amplitude
Probing TechniqueRXMS (Resonant X-ray Magnetic Scattering)
60 eV
(20.7 nm)
Slide7Magnetization
Amplitude Probing TechniqueRXMS (Resonant X-ray Magnetic Scattering)XUV probe – spatial resolutionNo need for an external magnetic fieldHolds information on the magnetic structure of the sample
Low efficiency (10-6)Requires a specific magnetic structureMagnetization must be out-of-plane
How to produce short XUV pulses?
Slide8Experimental
Details
High Harmonics
G
eneration
T
hree-step model,
P. B.
Corkum
, Phys. Rev. Lett. 71, 1994 (1993)
T
unnel ionisation
Propagation
Recombination
Slide9Experimental
DetailsHigh Harmonics GenerationLaser : 800 nm, 50 fsGas : neon
Slide10Experimental
DetailsSetup
Multilayer
focussing mirror
Gas cell
(HHG)
CCD
Filter
Filter
Beamstop
Delay
line
Focussing mirror
Focussing
mirror
Beamsplitter
Sample
Slide11Experimental
DetailsSampleSi3N4(30nm
) / Pt(2nm) / [Co(0.6nm) Pt(0.8nm)]20 / Al(3nm)Scale: 1µm
Slide12Results
Slide13Results
Wavelength scaling
Slide14Conclusion and
ProspectsUltrafast optical demagnetization measurements by RXSM in ALLS laboratoryNew parametersWavelengthPulse durationNext step
Spatial resolution
Slide15Acknowledgments
Thanks to Vincent Cardin, Dr.Tadas Balciunas, Antoine Laramée and to my supervisor, Pr. François Légaré.
Coming upPresentation at the Frontiers in Optics 2017 conference (In revision)