Regensburg 2007 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session

MM 20.41: Poster

Dienstag, 27. März 2007, 14:45–18:00, Poster C

Optical investigations on Fe_1−xCo_xSi single crystals using Raman spectroscopy under high pressure and far-infrared ellipsometry — •Ivan Jursic¹, Dirk Menzel¹, Pavlo Popovich², Alexander Boris², and Joachim Schoenes¹ — ¹Institut für Physik der Kondensierten Materie, TU Braunschweig, Mendelsohnstrasse 3, 38106 Braunschweig — ²Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart

Single crystals of Fe_1−xCo_xSi grown by the tri-arc Czochralski technique have been investigated using far-infrared spectroscopic ellipsometry. The band gap of the semiconductor FeSi, which is 33 meV at low temperatures, is filled with electrons when the temperature is increased. In the far-infrared range four infrared phonons can be identified. The full width of half maximum (FWHM) of these oscillators show different behaviour for the varying Co concentration. While for low Co content the FWHM of all phonons increases with rising temperature, for intermediate Co concentrations some of the peaks show a maxmimum in width as function of temperature. Also the oscillator strength has an unusual temperature dependence for certain phonons and concentrations. This striking behaviour is interpreted in terms of an electron–phonon interaction. The infrared data are compared to additional Raman investigations which have been performed with a diamond anvil pressure cell under high pressure.