Complex conductance of ultrathin La₂₋xSrxCuO₄ films and heterostructures

• Опубліковано в: : Физика низких температур
• Дата: 2015
• Автори: Gasparov, V.A., Božović, I.
• Формат: Стаття
• Мова: Англійська
• Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2015
• Теми: Свеpхпpоводимость, в том числе высокотемпеpатуpная
• Онлайн доступ: https://nasplib.isofts.kiev.ua/handle/123456789/128284
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Complex conductance of ultrathin La₂₋xSrxCuO₄ films and heterostructures / V.A. Gasparov, I. Božović // Физика низких температур. — 2015. — Т. 41, № 12. — С. 1237–1242. — Бібліогр.: 34 назв. — англ.

We used atomic-layer molecular beam epitaxy to synthesize bilayers of a cuprate metal (La₁.₅₅Sr₀.₄₅CuO₄)
 and a cuprate insulator (La₂CuO₄), in which each layer is just one unit cells thick. We have studied the magnetic
 field and temperature dependence of the complex sheet conductance, σ(ω), of these films. Experiments have
 been carried out at frequencies between 2–50 MHz using the single-spiral coil technique. We found that: (i) the
 inductive response starts at ∆T = 3 K lower temperatures than Re σ(T), which in turn is characterized by a peak
 close to the transition, (ii) this shift is almost constant with magnetic field up to 14 mT; (iii) ∆T increases sharply
 up to 4 K at larger fields and becomes constant up to 8 T; (iv) the vortex diffusion constant D(T) is not linear
 with T at low temperatures as in the case of free vortices, but is rather exponential due to pinning of vortex cores,
 and (v) the dynamic Berezinski–Kosterlitz–Thouless (BKT) transition temperature occurs at the point where
 Y = (lω/ξ₊)²
 = 1. Our experimental results can be described well by the extended dynamic theory of the BKT
 transition and dynamics of bound vortex–antivortex pairs with short separation lengths.