Two-dimensional ferromagnetic correlations above Tc in the Naturally layered CMR manganite La{sub 2-2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} (x = 0.3-0.4).
Neutron diffuse scattering in the form of rod-like features are observed in single crystals of the layered CMR material La{sub 2{minus}2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} (x=0.4,0.36), consistent with the presence of 2D ferromagnetic spin correlations. These diffuse features are observed over a wide temperature region, however, their coherence length does not appear to diverge at T{sub c}, although there is evidence of the development of three-dimensional correlations around ferromagnetic reflections of the 3D-ordered magnetic structure close to T{sub c}. Quasi-elastic neutron scattering on a ceramic sample of x = 0.3 shows that the lifetime of these ferromagnetic correlations increases at T {r_arrow} T{sub c}. They exhibit a spin-diffusion constant above T{sub c} of {approximately}5 meV {angstrom}{sup 2}, much lower than that reported for La{sub 2/3}Ca{sub 1/3}MnO{sub 3}. We discuss the relationship of these magnetic correlations to models of the ferromagnetic transition in CMR compounds.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10689
- Report Number(s):
- ANL/MSD/CP-95904; TRN: AH200127%%274
- Resource Relation:
- Conference: 43rd Annual Conference on Magnetism and Magnetic Materials, San Francisco, CA (US), 01/06/1998--01/09/1998; Other Information: PBD: 23 Mar 1998
- Country of Publication:
- United States
- Language:
- English
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