1. Artifacts in the characterization of skin layers and ultrathin films by X-ray diffraction X. Marti, V. Holy Charles University, Prague P. Ferrer, T. Schulli ESRF, Grenoble J. Herrero-Albillos BESSY, Berlin J. Narvaez, G. Catalan CIN2, Barcelona N. Barrett, CEA, Gif-sur-Yvette M. Alexe MPI, Halle EMRS, Warsaw, SEPT 2011xavi.mr@gmail.com D. Pesquera, F. Sanchez, G. Herranz, J. Fontcuberta ICMAB, Barcelona Substrate Thin film, t < 10 nm Out-of-plane parameter? 12 Conventional XRD Grazing incidence diffraction

2. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Substrate Thin film, t < 10 nm Incoming X-rays

3. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Substrate Thin film, t < 10 nm Incoming X-rays

4. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Substrate Thin film, t < 10 nm Incoming X-rays

5. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Substrate Thin film, t < 10 nm Incoming X-rays

6. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Substrate Thin film, t < 10 nm Incoming X-rays

7. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Substrate Thin film, t < 10 nm Incoming X-rays

8. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com |E SL (w)| 2 = |E S (w) + E L (w)| 2 |E 0 SL (w)| 2 = |E S (w)| 2 + |E L (w)| 2

9. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com |E SL (w)| 2 = |E S (w) + E L (w)| 2 |E 0 SL (w)| 2 = |E S (w)| 2 + |E L (w)| 2

10. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com How relevant this issue could be (1/2): Samples grown at ICMAB

11. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Samples grown at ICMAB |E SL (w)| 2 = |E S (w) + E L (w)| 2 |E 0 SL (w)| 2 = |E S (w)| 2 + |E L (w)| 2

12. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com How relevant this issue could be (1/2): Samples grown at ICMAB

13. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com How relevant this issue could be (2/2): Samples courtesy of A. Gruverman I0I0 Measured peak is at … …w = 22.24 deg The corresponding “c” is at … 21.84 deg !!!

14. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com How relevant this issue could be (2/2): Samples courtesy of A. Gruverman True lattice parameter Apparent lattice parameter I0I0 Measured peak is at … …w = 22.24 deg The corresponding “c” is at … 21.84 deg !!!

15. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com How relevant this issue could be (2/2): Sample courtesy of A. Gruverman I0I0 21.84 deg  4.14 Angstrom (fit) 22.24 deg  4.07 Angstrom (peak-pick) Measured peak is at … …w = 22.24 deg The corresponding “c” is at … 21.84 deg !!! FE Measurement courtesy of P. Zubko

16. 1.Small changes of the out-of-plane parameter 2.…and confined in a few (?) nm thick topmost surface http://henke.lbl.gov/optical_constants/ Single crystal αiαi EiEi EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Scenario # 2: a thin skin layer of a substrate

17. EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Correction for refraction

18. To circumvent refraction we scanned both energy and incidence angle EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com Color scale indicates the information depth For the particular case of BiFeO 3, for instance:

19. Measured Corrected BULKSKIN Q Q Changing the energy (no refraction correction required) EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com

20. Measured Corrected Changing the angles BULKSKIN Changing the energy (no refraction correction required) EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com

21. Concluding remarks 1)For the extraction of lattice parameters it is highly recommended to fit simultaneously both the substrate and the thin film using a dynamical or semi-kinematical model. 2)For the determination small changes of lattice parameters, in grazing incidence geometry, changing the energy may be more useful than changing the angles Thank you very much for your attention! xavi.mr@gmail.com EMRS, Warsaw, SEPT 2011 xavi.mr@gmail.com