2009 年 117 巻 1365 号 p. 612-615
During the last few years the studies on the divalent ion substituted rare earth manganites R1-xAxMnO3 (R = rare earth, A = alkaline earth ions), gained impetus after the compound were found to show colossal magnetoresistance. The physical properties of the substituted manganites depend on their structure, composition and oxidation states of Mn ions. Doping of the divalent metal ions in LaMnO3 induces ferromagnetism due to the change in the oxidation state of Mn ions. This indicates that the valence state of Mn ions play a key role in the tuning of the physical properties of manganites. In the present work, we study the effect of Co ions substitution at Mn side in La0.7Ca0.3Mn1-xCoxO3 (x = 0.01-0.05) thin films. Thin films of La0.7Ca0.3Mn1-xCoxO3 were grown epitaxially at 700°C under the oxygen pressure of 300 mTorr using pulsed laser deposition technique on LaAlO3 (001) substrate. X-ray diffraction study infers that all films grow epitaxially along the c-axis. The field cooled magnetization measured as a function of temperature indicates that all film exhibits ferromagnetic (FM) to paramagnetic (PM) transition with increase in the temperature. Moreover, the doping of Co affects the colossal magnetoresistance (CMR) effect in the present materials.
