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Author Argyriou, D. N. ♦ Mitchell, J. F. ♦ Radaelli, P. G. ♦ Bordallo, H. N. ♦ Cox, D. E. ♦ Medarde, M. ♦ Jorgensen, J. D.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ LANTHANUM COMPOUNDS ♦ STRONTIUM COMPOUNDS ♦ MAGNETORESISTANCE ♦ LANTHANUM OXIDES ♦ STRONTIUM OXIDES ♦ LAYERS ♦ CRYSTAL STRUCTURE ♦ NEUTRON DIFFRACTION ♦ X-RAY DIFFRACTION ♦ CRYSTAL LATTICES ♦ TEMPERATURE RANGE 0000-0013 K ♦ TEMPERATURE RANGE 0065-0273 K ♦ SPIN ♦ MAGNETIZATION
Abstract We report on the temperature dependence of the crystal and magnetic structure of the layered colossal magnetoresistive manganite, La{sub 2{minus}2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7}, x=0.3. Neutron-diffraction measurements show that the insulator-metal (IM) transition (T{sub IM}) at {approximately}100 K is accompanied by a ferromagnetic (FM) ordering of spins within MnO{sub 6} bilayers ({ital intrabilayer} coupling), but with an antiferromagnetic coupling between neighboring bilayers ({ital interbilayer} coupling). Below T{sub IM}, the Mn spins rotate from {approximately}45{degree} inclination to the {ital c} axis until they are almost parallel to the {ital c} axis at 5 K. Coincident with this spin reorientation, a FM {ital c} axis component develops below 75 K. Evidence from both neutron and synchrotron x-ray-diffraction experiments suggest that the FM {ital c}-axis magnetic moment results from a second layered manganite phase with composition 0.3{approx_lt}x{approx_lt}0.32. This observation emphasizes the need for thorough examination of the homogeneity when measuring bulk properties (e.g., magnetization, transport) of nominally {ital x}=0.3 samples. Associated with the electronic and magnetic transitions, a pronounced lattice response along the {ital c} axis (observed in both phases) signals a transfer of charge into d{sub x{sup 2}{minus}y{sup 2}} orbitals in the low-temperature phase. That the lattice effects here are opposite in sign to those observed in the {ital x}=0.4 layered manganite points to the sensitivity of the spin-lattice-charge coupling to dopant concentration in these reduced-dimensionality manganites. {copyright} {ital 1999} {ital The American Physical Society}
ISSN 01631829
Educational Use Research
Learning Resource Type Article
Publisher Date 1999-04-01
Publisher Place United States
Journal Physical Review, B: Condensed Matter
Volume Number 59
Issue Number 13


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