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).

Conference · Mon Mar 23 04:00:00 EST 1998

OSTI ID:10689

Argyriou, D N

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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
COHERENCE LENGTH
CRITICAL TEMPERATURE
FERROMAGNETISM
LANTHANUM OXIDES
MANGANESE OXIDES
MONOCRYSTALS
NEUTRON DIFFRACTION
PHASE TRANSFORMATIONS
SPIN
STRONTIUM OXIDES