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The effect of oxygen deposition pressure on the structure and properties of pulsed laser deposited La{sub x}Ca{sub 1{minus}x}MnO{sub {delta}} films

Book ·
OSTI ID:392205
; ;  [1]
  1. Naval Research Lab., Washington, DC (United States); and others
Thin films ({approximately}1,000 {angstrom}) of La{sub x}Ca{sub 1{minus}x}MnO{sub {delta}} (x=0.67) were deposited onto LaAlO{sub 3} (100) substrates at 600 and 700 C. Varying the oxygen deposition pressure between 15 and 400 mTorr systematically changed the oxygen concentrations in the as deposited films. As-deposited films exhibited an orthorhombic structure with an oxygen pressure dependent lattice parameter. The films were highly oriented as characterized by narrow x-ray {omega}-scans (FWHM {le} 0.16--0.70{degree}). At low pressures, the films were preferentially (202) oriented while at high pressures deposited films had a (040) preferred orientation. A 900 C anneal in flowing oxygen for a film deposited at low oxygen pressures resulted in a decrease in the lattice parameter (associated with an increase in {delta}) and a change in the preferred orientation from (202) to (040). The resistivity as a function of temperature (R(T)) showed a significant variation as a function of growth conditions. At 600 C, the peak in the resistivity curve (T{sub m}) varied between 73 and 93 K for P(O{sub 2}) = 15 to 400 mTorr, while at 700 C, T{sub m} was {approximately}150 K. For films deposited at 500 C, the resistivity was reduced by a factor of 10{sup 3} for H = 9T and T{sub m} was shifted to 150 K. The activation energy associated with the semiconducting phase was approximately the same for all as-deposited films ({approximately}100 meV).
OSTI ID:
392205
Report Number(s):
CONF-951155--; ISBN 1-55899-304-5
Country of Publication:
United States
Language:
English