Slow Relaxation of Resistance in Manganite Perovskite Nanoconstrictions

The time decay of the surface resistance RS(t) was measured for the La0.7Sr0.3MnO3perovskite nanocontacts obtained by break technique at liquid nitrogen.The corresponding time relaxation can be described by two-term formula: stretched exponential function and logarithmic dependence.The characteristic times τ1 and τ2 of the relaxation processes are of order of seconds and few tens of seconds, respectively.The appearance of both contributions evidences the existence of two sources of relaxation, which can be assigned to inhomogeneous changes of the angle between the magnetic moments of the neighboring Mn ions inside spin blocks (τ1) and between the spin blocks (τ2) occurring near surface of the nano-electrodes.Similar to magnetic viscosity, the dependence of resistance viscosity SR on basis current is characterized by bell-shaped curve.These results point out the important role of the structural arrangements of the Mn-ions into spin blocks on the surfaces electrodes of the nanocontact.