Two-dimensional ferromagnetic correlations above T{sub C} in the naturally layered CMR manganite La{sub 2{minus}2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} (x=0.3{endash}0.4) (invited)
- Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Neutron diffuse scattering in the form of rod-like features has been 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}5meV{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. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 627970
- Report Number(s):
- CONF-980102-; ISSN 0021-8979; TRN: 98:006291
- Journal Information:
- Journal of Applied Physics, Vol. 83, Issue 11; Conference: 7. joint MMM-intermag conference, San Francisco, CA (United States), 6-9 Jan 1998; Other Information: PBD: Jun 1998
- Country of Publication:
- United States
- Language:
- English
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