6533b854fe1ef96bd12af201

RESEARCH PRODUCT

Direct observation of Drude behavior in the heavy-fermion by broadband microwave spectroscopy

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Abstract Previous optical studies on the heavy-fermion system UPd 2 Al 3 down to frequencies of about 1 cm - 1 ( = 30 GHz ) revealed a well-pronounced pseudogap at low frequencies (below 3 cm - 1 ) that was attributed to magnetic correlations. Thus, the optical conductivity at even lower frequencies is of notable interest because the Drude roll-off (the high-frequency characteristic of a metal which will give information on the quasiparticle dynamics) remained hidden at extremely low frequencies. Using a novel cryogenic broadband microwave spectrometer employing the Corbino geometry we have studied the complex optical conductivity of UPd 2 Al 3 thin films in the frequency range from 45 MHz to 20 GHz at temperatures from 1.65 to 300 K . Our spectra reveal the emergence of a strong Drude-like conductivity roll-off at frequencies of only a few GHz as the temperature is decreased (in agreement with the increase of the DC conductivity).