ELECTRICAL AND MAGNETORESISTIVE PROPERTIES OF THE Ag/La2/3Sr1/3MnO3 POINT-PROBE CONTACTS

We report electrical and magnetoresistive properties of Ag point-probe contacts formed by attaching the bent Ag wire (empty set = 0.25 mm) to the top of the La2/3Sr1/3MnO3 (LSMO) thin film magnetron sputtered at 800 degrees C on MgO(100) single crystal substrates. Significant contact magnetoresistance values (up to 13% at T = 295 K and mu H-0 = 0.73 T) have been measured for the Ag/LSMO junctions by applying a 3 point-probe method. The origin of both temperature-dependent resistance and magnetoresistance of the Ag/LSMO contacts has been explained taking into account the dominating role of spreading resistance. It was found that keeping of the films in air for 1 month as well as ultrathin overlayers (d similar to 3-5 nm) of the highly resistive multiferroic BiFeO3 magnetron sputtered onto the manganite film resulted in a significant increase of contact resistance and reduced magnetoresistance values.