Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 27: Superconductivity: Cuprate Superconductors

TT 27.2: Talk

Wednesday, March 28, 2012, 11:45–12:00, H 2053

Optical investigation of nominally undoped Pr₂CuO₄ films — •G. Chanda¹, A. V. Pronin¹, R. P. S. M. Lobo², J. Wosnitza¹, H. Yamamoto³, and M. Naito⁴ — ¹Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — ²LPEM, ESPCI-ParisTech, CNRS, UPMC, Paris, France — ³NTT Basic Research Laboratories, NTT Corporation, Kanagawa, Japan — ⁴Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo, Japan

Superconducting Pr₂CuO₄ films with T^′ structure and T_c beetween 25 and 27 K have been investigated by different optical methods in a wide frequency range (5 – 55000 cm⁻¹) and for temperatures from 2 to 300 K. From the infrared reflectivity spectra, a superconducting gap of 2Δ₀ = 17 meV = 7.4 k_B T_c is estimated. Absolute values of the London penetration depth (λ_L) have been calculated from phase-sensitive teraherz measurements. The zero-temperature limit of λ_L is 1.6 µm. The overall temperature dependence of λ_L shows a behavior typical for the cuprates. However, a closer look on the penetration depth at low temperatures reveals a flattening of the temperature dependence. We find λ_L(T)∝ Tⁿ with n = 2.8 ± 0.2.