THICKNESS DEPENDENCE OF MAGNETORESISTANCE IN LA-CA-MN-O EPITAXIAL-FILMS

Colossal magnetoresistance in excess of 10(6)% has been obtained (at 110 K, H=6 T) in epitaxially grown La-Ca-Mn-O thin films. The as-deposited film exhibits a substantial magnetoresistance value of 39 000%, which is further improved by heat treatment. The magnetoresistance is found to be strongly dependent on film thickness, with the value reaching the maxima at similar to 1000 Angstrom thickness, and then reduced by orders of magnitude when the film is made thicker than similar to 2000 Angstrom. This behavior is interpreted in terms of lattice strain in the La-Ca-Mn-O films. (C) 1995 American Institute of Physics.