Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: CE: Heavy Fermions
TT 26.12: Vortrag
Mittwoch, 24. März 2010, 17:15–17:30, H21
Drude response of slow and fast electrons in the heavy-fermion compound UNi2Al3 — •Marc Scheffler1, Julia P. Ostertag1, Katrin Steinberg1, Martin Dressel1, and Martin Jourdan2 — 11. Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany — 2Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany
The unusual metallic behavior of heavy-fermion compounds at low temperatures is caused by mobile charge carriers with a large effective mass. This mass enhancement (compared to normal electrons) goes hand in hand with a reduction of the transport scattering time, which can directly be studied with optical spectroscopy: the characteristic Drude roll-off moves to very low frequencies. Here we combine microwave and THz spectroscopy to study thin films of the heavy-fermion compound UNi2Al3 in a broad frequency range.
At frequencies of a few GHz, a full Drude response indicates the dynamics of the heavy electrons in UNi2Al3. Surprisingly, at considerably higher frequencies (around 300 GHz) we observe a similar structure that is very reminiscent of Drude behavior. We interpret these two features as the Drude response of - at low frequencies - correlated, slow electrons and - at higher frequencies - uncorrelated, fast electrons. The temperature dependence and anisotropy of these two Drude roll-offs correspond to each other. These results also shed new light on previous studies of the related compound UPd2Al3.