Millimeter-wave study of London penetration depth temperature dependence in Ba(Fe₀.₉₂₆Co₀.₀₇₄)₂As₂ single crystal

• Дата: 2011
• Автори: Barannik, A.A., Cherpak, N.T., Ni, N., Tanatar, M.A., Vitusevich, S.A., Skresanov, V.N., Canfield, P.C., Prozorov, R., Glamazdin, V.V., Torokhtii, K.I.
• Формат: Стаття
• Мова: English
• Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2011
• Назва видання: Физика низких температур
• Теми: Письма pедактоpу
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/118638
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Millimeter-wave study of London penetration depth temperature dependence in Ba(Fe₀.₉₂₆Co₀.₀₇₄)₂As₂ single crystal / A.A. Barannik, N.T. Cherpak, N. Ni, M.A. Tanatar, S.A. Vitusevich, V.N. Skresanov, P.C. Canfield, R. Prozorov, V.V. Glamazdin1, K.I. Torokhtii // Физика низких температур. — 2011. — Т. 37, № 8. — С. 912–915. — Бібліогр.: 29 назв. — англ.

In-plane surface Ka-band microwave impedance of optimally doped single crystals of the Fe-based superconductor Ba(Fe₀.₉₂₆Co₀.₀₇₄)₂As₂ (Tc = 22.8 K) was measured. Sensitive sapphire disk quasi-optical resonator with high-Tc cuprate conducting endplates was developed specially for Fe-pnictide superconductors. It allowed finding temperature variation of London penetration depth in a form of power law, namely Δλ(T) ∼ Tn with n = 2.8 from low temperatures up to at least 0.6Tc consisted with radio-frequency measurements. This exponent points towards nodeless state with pairbreaking scattering, which can support one of the extended s-pairing symmetries. The dependence λ(T) at low temperatures is well described by one superconducting small-gap (Δ ≅ 0.75 in kTc units, where k is Boltzman coefficient) exponential dependence.