Temperature dependences of an excess current in contacts Ag/MgB2 (squares) and the parameter of the energy gap Δ(T) (circles) as well as the dependence of resistance in MgB2 with Tc ≈ 39 K.
The conductivity of an Andreev contact Ag/Bi2223 (Tc = 110 K) at the temperatures T = 77, 95, 101, 104, 110 (Tc ), 116, 122, 134, 146, 170, 182 K (top to bottom). Insets: schemes of an ordinary Sharvin contact (a) and combined contact made on a thin film covering a surface of Bi2223 (b). A circle indicates the contact area where a bias voltage applied to the contact is localized.
The I-V characteristics of a contact Ag/Bi2223 with Tc = 110 K at the temperatures T = 77, 110 (Tc ), 152, 182, 191, 200 and 206 K, and also in the normal state at 250 K (dotted line). Insets: (a) the dependence R(T) for Bi2223, (b) the temperature dependences of the excess current I exc (for V = 200 mV) and the contact conductivity dI/dV (for V = 0.01 V) (arbitrary units).
The temperature dependence of an excess current obtained from the data in Fig. 3 for V = 200 mV. Inset: the Andreev reflection of electrons (closed circles) with formation of Cooper pair and hole (open circle).
Article metrics loading...
Full text loading...