Magnetic and magnetoresistance studies on radio frequency sputtered La-Pb-Mn-O films

Results on structural and magnetic characterization of radio frequency sputtered thin films of La0.74Pb0.26MnOz on (100) Si are presented. Stoichiometric films with a thickness of 0.6 mu m showing (110) textured growth were deposited in a mixed argon-oxygen atmosphere. The low temperature magnetization is 10% smaller than the expected value for a collinear ferromagnetic order in the oxide. Zero-field resistivity data show a metal-to-semiconductor transition centered at T-ms=250 K. Data on magnetoresistance (MR)=[rho(0)-rho(H)]/rho(0) versus temperature reveal the following important features: (i) a maximum value of 22% for H=2 T at the metal-to-insulator transition temperature, (ii) MR value of 15%-22% over the entire temperature range 4.2-300 K, and (iii) a substantial MR, similar to 10% even at temperatures as high as 380 K, well above the Curie temperature. Data on the temperature dependence of ferromagnetic resonance linewidth at 9.4 GHz show a discontinuity at T-ms. (C) 1996 American Institute of Physics.