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Anomalous microwave conductivity coherence peak in c-axis MgB2 thin film

B. B. Jin·T. Dahm·A. I. Gubin·Eun-Mi Choi·Hyun Jung Kim·Sung-IK Lee·W. N. Kang·N. Klein
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Abstract

The temperature dependence of the real part of the microwave complex conductivity at 17.9 GHz obtained from surface impedance measurements of two c-axis oriented MgB2 thin films reveals a pronounced maximum at a temperature around 0.6 times the critical temperature. Calculations in the frame of a two-band model based on Bardeen-Cooper-Schrieffer (BCS) theory suggest that this maximum corresponds to an anomalous coherence peak resembling the two-gap nature of MgB2. Our model assumes there is no interband impurity scattering and a weak interband pairing interaction, as suggested by bandstructure calculations. In addition, the observation of a coherence peak indicates that the pi-band is in the dirty limit and dominates the total conductivity of our films

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B. B. Jin, T. Dahm, A. I. Gubin, Eun-Mi Choi, Hyun Jung Kim, Sung-IK Lee, W. N. Kang, N. Klein. 2003-08-07. Anomalous microwave conductivity coherence peak in c-axis MgB2 thin film. https://doi.org/10.1103/physrevlett.91.127006

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