Abstract :
The magnetic switching processes in point contacts (PC), which is made of the La0.7 Sr0.3 MnO3 perovskite ceramic, are studied as a function of the dc current passing through the nanoconstriction. Due to the close relation between the transport properties and the magnetization in manganite compounds, the resistivity measurements provide an excellent indirect method to characterize the magnetic switching processes observed in the atomic scale constrictions. Based on this, we interpret the jumps of the PC conductance by the integer multiples of the conductance quantum (e^2/h) as due to the magnetization configuration reorientation in the Mn-ions clusters at the surface of the nanoconstriction. This switching can be understood in the terms of the exchange of the angular momentum between the spinpolarized current and the magnetic moments of the cluster situated between the electrodes or on their surfaces.
