Intrinsic properties of doped lanthanum manganite
- Stanford Univ., CA (United States). Dept. of Applied Physics
- Hewlett-Packard, Palo Alto, CA (United States)
An investigation designed to display the intrinsic properties of perovskite manganites was accomplished by comparing the behavior of bulk samples with that of thin films; the results show the colossal magneto resistance at very low temperatures is not an intrinsic property of the thermodynamically stable 1/3 doped material. Epitaxial 1,500 {angstrom} films of perovskite La{sub 0.67}Ca{sub 0.33}MnO{sub 3} and La{sub 0.67}Sr{sub 0.33}MnO{sub 3} were grown by solid source chemical vapor deposition on LaAlO{sub 3} and post annealed in oxygen at 950 C. Below Tc/2 the intrinsic magnetization decreases as T{sup 2} (as can be expected for itinerant electron ferromagnets) while the intrinsic resistivity increases proportional to T{sup 2}. The constant and T{sup 2} coefficients of the resistivity are largely independent of magnetic field and alkaline earth element (Ca, Sr or Ba). The authors identify three distinct types of negative magnetoresistance. The largest effect is observed near the Curie temperature and is likely to be due to magnetic critical scattering. There is also magnetoresistance associated with the net magnetization of polycrystalline samples. The high temperature (above {Tc}) resistivity at La{sub 0.67}Ca{sub 0.33}MnO{sub 3} is consistent with small polaron hopping conductivity with a transition at 750K, while La{sub 0.67}Sr{sub 0.33}MnO{sub 3} does not exhibit activated conductivity until about 500K, well above {Tc}. The limiting low and high temperature resistivities may place a limit on the maximum possible magnetoresistance of these materials.
- OSTI ID:
- 392208
- Report Number(s):
- CONF-951155-; ISBN 1-55899-304-5; TRN: 96:028546
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 27 Nov - 1 Dec 1995; Other Information: PBD: 1996; Related Information: Is Part Of Epitaxial oxide thin films 2; Speck, J.S. [ed.] [Univ. of California, Santa Barbara, CA (United States)]; Fork, D.K. [ed.] [Xerox Palo Alto Research Center, CA (United States)]; Wolf, R.M. [ed.] [Philips Research Labs., Briarcliff Manor, NY (United States)]; Shiosaki, Tadashi [ed.] [Kyoto Univ. (Japan)]; PB: 577 p.; Materials Research Society symposium proceedings, Volume 401
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LANTHANUM OXIDES
CHEMICAL VAPOR DEPOSITION
MAGNETIC PROPERTIES
MAGNETORESISTANCE
STRONTIUM OXIDES
CALCIUM OXIDES
MANGANESE OXIDES
PEROVSKITES
LASERS
SUBSTRATES
LANTHANUM COMPOUNDS
ALUMINATES
ANNEALING
OXYGEN
X-RAY DIFFRACTION
CUBIC LATTICES
MAGNETIZATION
CURIE POINT
MAGNETIC FIELDS
TEMPERATURE DEPENDENCE
EXPERIMENTAL DATA