Giant magnetoresistance phenomenon in laser ablated La{sub 0.6}Y{sub 0.07}Ca{sub 0.33}MnO{sub x} thin films
- North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering
- Oak Ridge National Lab., TN (United States). Solid State Div.
Microstructural and magnetoresistance properties of La{sub 0.6}Y{sub 0.07}Ca{sub 0.33}MnO{sub x} (Y-doped LCMO) thin films grown in-situ by pulsed laser ablation have been studied. Transmission electron microscopy and x-ray diffraction measurements have shown that the Y-doped LCMO thin films grow epitaxially on (100) LaAlO{sub 3} substrates and are cubic with a lattice parameter of 3.849 {angstrom}. The as-deposited films exhibited a metal-insulator transition at 130 K and a giant magnetoresistance (GMR) at 125 K with a MR ratio (dR/R{sub H}) of 1,500% in the presence of a magnetic field of 6 Tesla. Such a colossal value of MR ratio for as-deposited Y-doped LCMO films is quite promising keeping in view the fact that these films were unannealed and not optimized. The authors ascribe this magnetoresistance to spin-dependent electron scattering coupled with the presence of intervening O{sup 2{minus}} ions across Mn{sup 3+} and Mn{sup 4+} with suppressed separation between Mn-O layers caused by smaller sized Y-dopant. The effect of annealing on the positive-shift of metal-insulator transition temperature and the improvement in GMR ratio has also been discussed. The authors report a non-ohmic response in the Y-doped LCMO films which is observed only in the region of the resistance peak and lends support to a conduction mechanism in these materials based on spin-dependent scattering of electrons.
- OSTI ID:
- 490847
- Report Number(s):
- CONF-951155--; ISBN 1-55899-300-2
- Country of Publication:
- United States
- Language:
- English
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