soft x-ray scattering at esrf: a brief overview peter bencok european synchrotron radiation facility...

SOFT X-RAY SCATTERINGAT ESRF: A BRIEF OVERVIEW

Peter BencokEuropean Synchrotron Radiation Facility

Grenoble, France

OUTLINE

ID8 CharacteristicsScattering instruments:

•High field magnet setup•Diffractometer setup

Commissioning resultsExperimental resultsDevelopmentConclusion

ID8 CHARACTERISTICS

2 undulators APPLE II100 % polarized light of any polarization

Dragon monochromatorEnergy range 400-1500 eVResolving power 5000-10000

Flux at the sample 1013 photons/s/0.1%BWBeam size 1 mm x 0.1 mm5 experimental stations

HIGH FIELD MAGNET SETUP

Generally devoted to XMCD7 Tesla superconducting magnetSample temperature 7-300 KHorizontal scattering planeDiode detector with horizontal slitPrep. chamber :

•VT STM, LEED and AES+ sample environment, preparation- reduced geometry

DIFFRACTOMETER SETUP

5-circle goniometer in 800 mm chamberVertical scattering planeEntrance slits and pinholesSilicon pin diode with detector slitsUVH compatible

Timescale :Jan 2001 Call for tenderOct 2002 DeliveryOct 2003 First user experiment

DIFFRACTOMETER SETUP

Coaxially mounted external 2-circle stage coupled through differentially pumped rotary sealsOther inside vacuum motorsBase pressure < 1x10-10 mbarPreparation facility: chamber with ion sputtering, annealing, evaporationSample stage connected to open-flow He cryostat that attains 80 K

COMMISSIONING RESULTS

W/C Multilayers

COMMISSIONING RESULTS

Off-specular scansFeGd films at the Fe L3

edge absorption edgeVarious 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 Imagnetic speckles

superlattice peaks

specular peak

x-ray beam

pinhole 10 µm

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

after 350 000 steps :Error ~ 0.4

320 lines~700 pixels between peaks Oversampling >2

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

EXPERIMENTAL RESULTS

40 nm GdFe180 nm period

(MFM)

-1 0 1

Point symmetric, correlation ~ 0.93

Fraunhofer fringes

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 superstructureHigh surface sensitivity

60 nm

0.2 0.4 0.6 0.8 1.0 1.2 1.4

1

2

3

4

5

6

hν = 778 (eVL3 )edge hν = 780 eV

( . )Intensity arb units

h

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

DEVELOPMENT

Sample cooling: from 80K down to 21 KMagnetic 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 analyzerArea 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 requestsfor HFM setup

Design of a diffractometerVersatility 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 DIAMONDN. BrookesS. StanescuR. Barret ESRFP. MarionP. van der LindenK. Larsson in memoriamA. Marty, G. Beutier CEAG. van der Laan SRST. Schulli CEAG. Bauer, J.Stangl UNIV LinzP. Ohresser SOLEILS. Rousset, V. Repain, S. Rohart UNIV Paris 6F. Scheurer IPCMS StrasbourgJ. B. Goedkoop, J. Peters, M. Vries AmsterdamJ. Miguel, O. Toulemonde, H. Luigjesp Amsterdam