Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.28: Poster

Mittwoch, 24. März 2010, 14:00–18:00, Poster D1

The ferromagnetic phase transition in Sr_1−xCa_xRuO₃ thin films studied by noise spectroscopy — •Adham Amyan¹, Pintu Das¹, Jens Brandenburg², Jens Müller¹, Melanie Schneider³, Vasily Moshnyaga³, and Philipp Gegenwart³ — ¹Physikalisches Institut, Goethe-Universität Frankfurt, Frankfurt am Main, Germany. — ²Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany. — ³Physikalisches Institut, Georg-August Universität Göttingen, Göttingen, Germany.

Fluctuation (noise) spectroscopy is a powerful tool to investigate the intrinsic dynamics of charge carriers coupled to lattice vibrations and defects, or magnetic and electronic excitations. In principle, one can access the autocorrelation function describing the kinetics of the fluctuating carriers. We employ an ac-technique to study the excess 1/f-type noise at different temperatures and magnetic fields for samples Sr_1−xCa_xRuO₃ with various Ca concentrations x. In particular, in our low-frequency studies we are interested in the energy distribution of fluctuators causing the excess noise in the vicinity of the ferromagnetic transition in the energy range of 1 meV-1 eV. To this end, we use a phenomenological random fluctuation model and compare the noise data to complementary measurements of the Hall effect. Also, we are investigating the differences of the low-temperature dynamical properties as a function of Ca doping, in particular close to the ferromagnetic quantum phase transition, where T_C→0 for x_c=0.7.

Work supported by the DFG through the Emmy Noether-program and SFB 602.