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LIGNE DE LUMIERE CASSIOPEE

Research Contents > Beamlines > CASSIOPÉE

General description: The CASSIOPEE beamline is a soft X-ray beamline dedicated to high resolution ARPES, spin-resolved photoemission and resonant spectroscopies in the 8 eV-1500 eV photon energy range. This wide energy range allows both surface and bulk studies of condensed matter. The beamline uses two undulators as a source with high flux and adjustable polarisation. The energy is selected by a high resolution PGM (Plane Grating Monochromator) with VLS (Variable Line Spacing) and VGD (Variable Groove Depth) gratings for best efficiency and purity of the light. After the monochromator, the beamline is divided into two branches, supplying photons to two end stations (Spin-resolved Photoemission, and High Resolution Angle-resolved Photoemission), both connected to a Molecular Beam Epitaxy chamber for sample growth and caracterisation.

Optics 
                 Undulators (HU256 and HU60)
                 Entrance Optics (M1)
                 Mono (BESTEC)
                 Varied Groove Depth Gratings (VGD)

 Experiments
                 Spin Resolved Photoemission (Cx1)
                 High Resolution Angle Resolved Photoemission (Cx2)
                The CASSIOPEE MBE (Cx3)
                The Samples
Staff/Contact

Energy Range : From 8 to 1500 eV
Energy Resolution: From 20000 to 70000 depending on the photon energy.
Sources: HU256 electromagnetic undulator (8 to 100 eV)
HU60 Apple II type undulator (100 to 1500 eV)

Flux on first optics: 1015 ph/s/0.1% bw.

Optics: -3-mirror set entrance optics
-Plane-grating monochromator (3 Variable Line Spacing-Variable Groove Depth gratings, working in the modified Petersen mode)
-Spin Resolved Photoemission branch: Focussing by a toroidal mirror (from 250x200 to 720x350 µm2 spot on the sample depending on the photon energy)
-High Resolution Photoemission branch: Pseudo-Wolter focussing (40x20 to 100x100 µm2 spot on the sample depending on the photon energy).

Sample Environment: 3 Ultra-high Vacuum chambers
-Molecular Beam Epitaxy chamber with surface science tools
-Spin Resolved Photoemission: Temperature from 25 to 400K, 1200 Oe magnetic field
-High Resolution Photoemission: Temperature from 4 to 400K

Photon flux on sample: 2x1013 ph/s/0.1% bw.

Detection: -Spin Resolved Photoemission: Scienta SES2002 electron analyzer coupled to a compact retarding field Mott detector.
-High Resolution Photoemission: Scienta R4000 electron analyzer with Wide Angle Lens.

Scientific Topics: Electronic and magnetic properties of low dimensional systems
-Highly correlated systems:
Complex oxides (Cobaltates, pnictides, cuprates, vanadates…)
Surfaces and interfaces (Sn/Ge, Sn/Si, Alkali/Si:B…)
-Topological insulators
-Materials for spintronics : Magnetic tunnel junctions, thin films of Heusler compounds
-Surfaces/Interfaces/nanoobjects:
metal/metal, metal/semiconductor, semiconductor/semiconductor
Molecules/surfaces, biological species/surfaces
-Graphene

 Publications de la ligne

 Actualités :

- Fin d’une controverse : révélation de la nature d’une « interface-modèle »

- Étude de supraconducteurs à haute température sur la ligne CASSIOPEE

- Microélectronique : un gaz d’électrons à la surface d’un isolant ouvre la voie du transistor multi-fonctions

- Prix Nobel de physique 2010 : le graphène à l'honneur

- Le graphène tient
ses promesses

- Jonctions tunnels et premiers spectres de photoémission résolue en spin sur CASSIOPEE

- Premières expériences de photoémission angulaire sur CASSIOPEE

 

 Poster de la ligne

 APS

 

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