Universal conductance fluctuations in Cu : Mn nanocontacts

Universal conductance fluctuations in Cu:Mn nano-contacts of different Mn c oncentrations c yield the phase coherence length L-phi which exhibits a min imum at c approximate to 100 ppm. Above this concentration which marks the onset of a spin-glass state below 0.2 K, L-phi depends on the magnetic fiel d range, rising to nearly the c = 0 value for B is an element of [9.5, 12.5 T] and leveling-off at a much lower value for B is an element of [0, 3 T]. These results demonstrate the recovery of phase coherence due to spin-glas s correlations and a strong magnetic field. (C) 2000 Elsevier Science B.V. All rights reserved.