PULSED-LASER DEPOSITION OF THIN-FILMS OF (LA1-XCAX)MNO3

Manganites of the series (La1-xCax)MnO3, with x = 0,0.1,0.3,0.5,0.7 an d 1.0, have been characterized in ceramic form and thin films have bee n prepared by pulsed laser deposition. Characterization techniques inc luded x-ray diffraction, conductivity and magnetoresistance, magnetiza tion and susceptibility, optical spectroscopy and the Faraday effect. Both the films and ceramics exhibit a maximum low-temperature conducti vity at x approximate to 0.3 which is coexistent with ferromagnetic or der. The negative magnetoresistance effect is qualitatively different for the x = 0.3 and x = 0.5 compositions. For x = 0.3 the magnetoresis tance peak occurs around the Curie point, whereas for x = 0.5 the onse t of magnetoresistance is somewhat below T-c and increases monotonical ly as T --> 0. The applied held appears to modify the magnetic order ( on the scale of the spin diffusion length) down to the lowest temperat ures for x = 0.5, but for x = 0.3 the ferromagnetic order is essential ly complete and collinear below the Curie point.