# Presentation: 693620

## SOFT X-RAY SCATTERING

- AT ESRF: A BRIEF OVERVIEW
- Peter Bencok
- European Synchrotron Radiation Facility
- Grenoble, France

## OUTLINE

- ID8 Characteristics
- Scattering instruments:
- High field magnet setup
- Diffractometer setup
- Commissioning results
- Experimental results
- Development
- Conclusion

## ID8 CHARACTERISTICS

- 2 undulators APPLE II
- 100 % polarized light of any polarization
- Dragon monochromator
- Energy range 400-1500 eV
- Resolving power 5000-10000
- Flux at the sample 1013 photons/s/0.1%BW
- Beam size 1 mm x 0.1 mm
- 5 experimental stations

## HIGH FIELD MAGNET SETUP

- Generally devoted to XMCD
- 7 Tesla superconducting magnet
- Sample temperature 7-300 K
- Horizontal scattering plane
- Diode detector with horizontal slit
- Prep. chamber :
- VT STM, LEED and AES
- + sample environment, preparation
- - reduced geometry

## DIFFRACTOMETER SETUP

- 5-circle goniometer in 800 mm chamber
- Vertical scattering plane
- Entrance slits and pinholes
- Silicon pin diode with detector slits
- UVH compatible

- Timescale :
- Jan 2001	Call for tender
- Oct 2002	Delivery
- Oct 2003	First user experiment

## DIFFRACTOMETER SETUP

- Coaxially mounted external 2-circle stage coupled through differentially pumped rotary seals
- Other inside vacuum motors
- Base pressure < 1x10-10 mbar
- Preparation facility: chamber with ion sputtering, annealing, evaporation
- Sample stage connected to open-flow He cryostat that attains 80 K

## COMMISSIONING RESULTS

- W/C Multilayers

## COMMISSIONING RESULTS

- Off-specular scans
- FeGd films at the Fe L3 edge absorption edge
- Various geometries allows different scattering channels

- Closure domains in FeGd alloy

## EXPERIMENTAL RESULTS

- Orbital ordering in TM oxides

*S. S. Dhesi et al., PH YSICAL REVIEW LETTERS 92(5), 56403-1-4 (2004)*

## EXPERIMENTAL RESULTS

- Magnetic speckles from nanolines I

*A. **Marty, G. Beutier, G. van der Laan et al.*

## EXPERIMENTAL RESULTS

- Magnetic speckles from nanolines II

- Phase retrieval problem :
*  **I = |****A****|2       I => ****A ***?
- Small number of unknown, with discrete values
- => simulated annealing monte carlo algorithm

*A. **Marty, G. Beutier, G. van der Laan et al.*

## EXPERIMENTAL RESULTS

- 40 nm GdFe
- 180 nm period
- (MFM)

- Magnetic speckle from stripe domains in transmission

*J. B. Goedkoop, J. Peters, M. Vries, J. Miguel, O. Toulemonde, H. Luigjesp et al.*

## EXPERIMENTAL RESULTS

- EuSe nanoislands

*T. Schulli et al., APPLIED PHYSICS LETTERS 84(14), 2661-3 (2004)*

## EXPERIMENTAL RESULTS

- Co self-organisated nanodot network
- Au/1 ML Co/Au(11,12,12)
- Looking for the magnetic superstructure
- High surface sensitivity

*S. Rousset**, **V. Repain, S. Rohart et al.*

## DEVELOPMENT

- Sample cooling: from 80K down to 21 K
- Magnetic field:
- 0.2 T pulsed perpendicular to the surface plane
- (in collaboration with Marty, van der Laan)
- 0.2 T static in the surface plane
- Polarization analysis: ML analyzer
- Area detector : CCD fixed on a flange
- Already done

## CONCLUSION

- Successfully used for variety of experiments (OO, speckle, diffraction from nanostructures)
- Nowadays ~3 weeks of user experiments per 6 months but still requests
- for HFM setup
- Design of a diffractometer
- Versatility vs specialization in multiD space (H, T, angles, UHV, ...)
- 	+	-
- UHV	in-situ prep	transfer, materials,...
- Mom transfer	more exp	space, T, H
- 	.........
-                               Modularity ?
- P.S. Different user requests for beam specification (speckle<>diffraction)

## ACKNOWLEDGMENT

- S. S. Dhesi	DIAMOND
- N. Brookes
- S. Stanescu
- R. Barret	ESRF
- P. Marion
- P. van der Linden
- K. Larsson	in memoriam
- A. Marty, G. Beutier	CEA
- G. van der Laan	SRS
- T. Schulli	CEA
- G. Bauer, J.Stangl	UNIV Linz
- P. Ohresser	SOLEIL
- S. Rousset, V. Repain, S. Rohart	UNIV Paris 6
- F. Scheurer	IPCMS Strasbourg
- J. B. Goedkoop, J. Peters, M. Vries	Amsterdam
- J. Miguel, O. Toulemonde, H. Luigjesp	Amsterdam