Temperature dependence of the electrical resistance of amorphous bismuth films
Abstract
The paper reports a study of the reversible temperature variation of the electrical resistance of thin (L = 10–130 Å) amorphous bismuth films deposited on substrates at liquid-helium temperatures. The superconducting fluctuations give rise to a small increase in the resistance near the superconducting transition temperature (Tc ≈ 2–5.5 °K). Above the temperature Tmax (∼ 10–14 °K) the resistance decreases, its variation being describable by the function R = R0 (1—ATn), which has been predicted for amorphous metals in a number of theoretical papers. When the contribution of the superconducting fluctuations at all arbitrarily high (as compared to Tc) temperatures is taken into account, the exponent n is equal to two in the vicinity of Tmax (up to ∼ 30 °K) and to unity at higher temperatures. When the contribution of the superconducting fluctuations at T > Tmax is neglected, the exponent n = 4 for the directly measured values. It turns out that the coefficient A depends on the film thickneess: it increases with decreasing the L. The observed laws governing the temperature dependence of the resistance of amorphous films are discussed on the basis of modem theoretical models.