Dresden 2003 – scientific programme

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DY: Dynamik und Statistische Physik

DY 37: Critical phenomena and phase transitions II

DY 37.6: Talk

Wednesday, March 26, 2003, 17:45–18:00, G\"OR/229

Grazing-incidence X-ray study of the charge density wave transition in NbSe₂ — •Bridget Murphy^1,2, Jochim Stettner^1,2, Micheal Sprung¹, Ingo Grotkopp¹, Martin Müller¹, Metin Tolan³, and Werner Press^1,4 — ¹Inst. für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, Leibnizstr. 19, 24098 Kiel, Germany — ²CLRC, Daresbury Laboratory, Warrington, WA4 4AD,UK. — ³Universität Dortmund, Experimentelle Physik I, 44221 Dortmund, Germany. — ⁴Institut Laue-Langevin, BP 156 - 38042 Grenoble Cedex 9, France.

We report the results of using grazing incidence X-ray diffraction studies on the charge density wave transition in 2H-NbSe₂, a Van der Waals bonded layered structure. The evolution of the satellite reflection has been observed above and below the critical angle of total external reflection allowing a penetration depth variation of between 25Å and 1000Å. We have successfully isolated the surface charge density wave structure on a high quality single crystal. Our central finding is that at the surface, the charge density wave transition occurs at a higher temperature than in the bulk. It is likely that we observe the unusual case defined as a ’surface transition’.