Andreev-reflection spectroscopy with superconducting indium — a case study

• Опубліковано в: Физика низких температур
• Дата: 2013
• ISSN: 0132-6414
• Автори: Gloos, K., Tuuli, E.
• Формат: Стаття
• Мова: Англійська
• Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2013
• Теми: К 75-летию со дня рождения И. К. Янсона
• Онлайн доступ: https://nasplib.isofts.kiev.ua/handle/123456789/118224
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Andreev-reflection spectroscopy with superconducting
 indium — a case study / K. Gloos, E. Tuuli // Физика низких температур. — 2013. — Т. 39, № 3. — С. 326–334. — Бібліогр.: 51 назв. — англ.

We have investigated Andreev reflection at interfaces between superconducting indium (Tc = 3.4 K) and several
 normal conducting nonmagnetic metals (palladium, platinum, and silver) down to T = 0.1 K as well as zinc
 (Tc = 0.87 K) in its normal state at T = 2.5 K. We analyzed the point-contact spectra with the modified onedimensional
 BTK theory valid for ballistic transport. It includes Dynes’ quasiparticle lifetime as fitting parameter Γ
 in addition to superconducting energy gap 2Δ and strength Z of the interface barrier. For contact areas from less than
 1 nm² to 10000 nm² the BTK Z-parameter was close to 0.5, corresponding to transmission coefficients of about
 80%, independent of the normal metal. The very small variation of Z indicates that the interfaces have a negligible
 dielectric tunneling barrier. Also Fermi surface mismatch does not account for the observed Z. The extracted value
 Z ≈ 0.5 can be explained by assuming that practically all of our point contacts are in the diffusive regime.