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Document type:
Zeitschriftenaufsatz 
Author(s):
Martínez, J. L.; B̈oni, P.; Shirane, G. 
Title:
Spin Dynamics in {{Ni}} near ${T}_{C}$: {{A}} High-Resolution Neutron Scattering Study 
Abstract:
We have studied the magnetic cross section in Ni below and above TC using unpolarized and polarized neutron scattering techniques. For temperatures near the Curie temperature (TC=631 K) and for a range of momentum transfer 0.2$<$q$<$0.4 A˚-1 (Brillouin zone width$\simeq$1.54 A˚-1), the spin waves renormalize as expected from extrapolating the results at smaller momentum transfer (q$<$0.2 A˚-1). At TC the spin waves merge into a broad single peak centered at zero-energy transfer, which is well described by a double-Lorentzian scattering function. Our results, below and above TC, agree with the predictions of the dynamic scaling theory in the area of (q,$\omega$) space and the range of temperatures investigated. This is in contrast with recent measurements which reported magnetic excitations at finite energies above TC. 
Journal title:
Physical Review B 
Year:
1985 
Journal volume:
32 
Month:
dec 
Journal issue:
11 
Pages contribution:
7037