Magnetic and transport properties of the system La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (0 < x {le} 0.50)
- Univ. of Texas, Austin, TX (United States)
Magnetic and transport measurements on the system La{sub 1-x}Sr{sub x} CoO{sub 3-{delta}}(0 < x {le} 0.50, {delta} = 0 for 0 {le} x < 0.30, and {delta} (x) {le} 0.06 for 0.30 {le} x {le} 0.50) have led to a phase diagram for this system. Upon Sr doping, the material segregates into hole-rich, metallic ferromagnetic regions and a hole-poor matrix similar to LaCoO{sub 3}. The Co ions of the ferromagnetic phase are in intermediate-spin configurations; the hole-poor matrix experiences a thermally induced low-spin to high-spin transition. For low Sr doping (x < 0.20), the hole-rich regions are isolated from one another and show superparamagnetic behavior below T{sub c}{approx}240 K; longrange magnetic order via frustrated intercluster interactions occurs below a superparamagnetic freezing temperature T{sub g} that increases with x. At x = 0.20, the coupling between the intermediate-spin, metallic ferromagnetic clusters within an interpenetrating matrix reaches a magnetic percolation threshold that orders the clusters ferromagnetically below T{sub c}{approx} 250 K. However, the electrical conduction in the ferromagnetic regions is modulated by the matrix, which has a spin state that varies with temperature. This causes a reentrant semiconductive behavior in the samples with 0.20 {le} x {le} 0.25. Metallic ferromagnetic behavior is found for 0.30 {le} x {le} 0.50 even though the presence of an interpenetrating hole-poor matrix persists to x = 0.50. A ferromagnetic fraction less than unity leads to peculiar magnetic properties that have been attributed in the literature to a magnetic {open_quotes}cluster glass.{close_quotes}
- OSTI ID:
- 210085
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 118; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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