Spin polarons in La{sub 1-x}Sr{sub x}CoO{sub 3} single crystals.

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Phys. Rev. B

DOI:https://doi.org/10.1103/PhysRevB.78.092201· OSTI ID:947531

Smith, R X; Hoch, M J. R.; Kuhns, P L; Moulton, W G; Reyes, A P; Boebinger, G S; Mitchell, J; Leighton, C

Nanoscale inhomogeneity in La{sub 1-x}Sr{sub x}CoO{sub 3} has been investigated in single-crystal samples for 0.05 {le} x {le} 0.30 using {sup 139}La and {sup 59}Co NMR to probe local magnetization. In contrast to polycrystalline samples, single crystals exhibit ferromagnetism only above the metal-insulator critical concentration x{sub C} = 0.17. However, over the entire doping range, the single crystals exhibit an unusually broad and asymmetric distribution of hyperfine fields, evidencing (local) spin-polaron formation that persists to temperatures as high as 200 K, well above the glass transition reported previously from bulk magnetization. Above x{sub C} the asymmetry decreases rapidly with increasing doping as polarons overlap to give rise to long-range ferromagnetism. A modified phase diagram is presented. The key features of the data are reproduced by a simple model in which Sr dopants trigger spin-polaron formation, a physical picture first proposed by de Gennes [Phys. Rev. 118, 141 (1960)].

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; NSF; State of Florida
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 947531
• Report Number(s): ANL/MSD/JA-60875
• Journal Information: Phys. Rev. B, Journal Name: Phys. Rev. B Journal Issue: 2008 Vol. 78; ISSN 1098-0121
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
DISTRIBUTION
FERROMAGNETISM
GLASS
MAGNETIZATION
MONOCRYSTALS
PHASE DIAGRAMS
POLARONS
PROBES
SPIN