Dresden 2011 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 51: Magnetic Half-metals and Oxides II
MA 51.8: Vortrag
Donnerstag, 17. März 2011, 12:45–13:00, HSZ 401
Systematic studies of ferromagnetic ordering in EuB6 — •Adham Amyan1, Pintu Das1, Mariano de Souza1, Michael Lang1, Peng Xiong2, Stephan von Molnár2, Zachary Fisk3, and Jens Müller1 — 1Physikalisches Institut, Goethe Universität, D-60438 Frankfurt (M). — 2Department of Physics MARTECH, Florida State University, Tallahassee, USA. — 3Department of Physics, University of California, Irvine, USA.
The ferromagnetic semimetal EuB6 recently has attracted renewed interest due to its rich transport and magnetic properties. In transport and thermodynamic measurements, two consecutive phase transitions at ∼ 12.6 K and 15.3 K are observed, where upon lowering the temperature a charge-localization transition via the overlap of magnetic polarons precede the ferromagnetic ordering. This behavior is discussed in terms of electronic phase separation and a percolative phase transition [1].
In this work, we performed fluctuation (noise) spectroscopy measurements of high-quality single crystals of EuB6 in order to investigate the dynamics of the charge carriers close to the above-mentioned transitions. In addition, higher-harmonics transport measurements reveal clear signatures of non-linear effects going along with the lower ferromagnetic transition. Furthermore, ultra high-resolution thermal expansion measurements reveal that lattice degrees of freedom are strongly coupled to both low-temperature transitions.
[1] X. Zhang, L. Yu, S. von Molnár, Z. Fisk and P. Xiong, PRL 103,106602 (2009)