Hamburg 2001 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 3: Schwere Fermionen
TT 3.1: Vortrag
Montag, 26. März 2001, 09:30–09:45, A
Pseudogap in the optical spectra of UPd2Al3 — •M Dressel1, B Gorshunov1, N Kasper1, K Petukhov1, D Peligrad1, M Huth2, and H Adrian2 — 1Physikalisches Institut, Uni-Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart — 2Institut für Physik, Uni-Mainz, Staudinger Weg 7, 55099 Mainz
The optical properties of thin film of heavy fermion (HF) compound UPd2Al3 were studied at frequencies 10 GHz up to 1.2 THz in the ranges of temperature 2 K <T< 300 K and of magnetic field up to 8 T. At T<25 K a well pronounced pseudogap with Eg ≈ 0.22 meV develops in the optical response; this feature does not arise from the gap in magnetic excitation spectra. We also found a narrow conductivity peak centered at zero frequency which is less than 1 cm−1 wide and which contains only a fraction of the delocalized carriers. Our findings may be a consequence of the hybridizaton gap inherent in HF; for UPd2Al3 the value is strongly reduced compared to the Kondo coupling energy due to low concentration of screening electrons (exhausting regime).