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TT: Tiefe Temperaturen

TT 3: Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter I

TT 3.5: Vortrag

Montag, 24. März 2003, 10:30–10:45, HSZ301

X-ray Standing Wave Photoemision Studies of YBa₂Cu₂O_{7 − δ} Single Crystals — •Sebastian Thiess¹, T.-L. Lee¹, C.T. Lin², B.C.C. Cowie¹, N. Brookes¹, C. Kunz¹, and J. Zegenhagen¹ — ¹ESRF, Grenoble, France — ²MPI-FKF, Stuttgart, Germany

The x-ray standing wave technique uses an interference field typically generated by the superposition of two x-ray waves during Bragg reflection. Monitoring the photoabsorption process via e.g. photoemission, real space structural information about specific elements inside or on the surface of a crystal can be obtained. Monitoring photoemission from valence bands, the partial density of states of the valence bands at particular sites within the unit cell can be determined. We have performed XSW measurements with YBa₂Cu₂O_{7 − δ} single crystals detecting core level and valence band photoemission. Clean crystal surfaces were prepared by cleaving at about 30K in UHV. XSW measurements were performed at low temperature and at room temperature using several YBCO(00l) reflections ranging from l = 1 at 0.5 keV up to l = 7 at 3.7 keV photon energy. XSW results for core level and valence band emission will be presented. The results of different surface preparation procedures will be discussed in the talk.