Antiferromagnetic neutron peaks

Inelastic neutron scattering(INS) measurements probe directly the imaginary part of the dynamical spin susceptibility. Therefore, it is of interest to analyze the role played by the electronic correlations in connection with the resonance peak seen by INS[3], This feature is well understood using various approaches[20, 21] as a result of the spin density wave(SDW) collective mode formation at co = coreSt i.e. when the denominator of the RPA spin susceptibility at the antiferromagnetic wave vector Q is close to zero. 

The low temperature heat capacities in the temperature range from 52-298 K are obtained from Todd s measurements (7). Two peaks at 193.5 K and 230.9 K were found in his heat capacity data. Below 50 K, the heat capacities were extrapolated using a combination of 1 Debye (0 = 139) and 2 Einstein (0 = 260) functions as suggested by Todd. This extrapolation yields the entropy from lattice contribution as 3.278 cal k" mol at 50 K. By neutron diffraction. Smith et al. ( ) found an antiferromagnetic transition at 7 K which indicates the existence of an unpaired electron in KOgCcr). We tentatively adopt S (50 K) = 4.656 1 cal K" mol" which includes both lattice (3.278 cal k" mol" ) and unpaired electron (Rtn2) contributions. Heat capacities above 298 K are estimated graphically. 

Fig. 21. Neutron scattering data from an antiferromagnetically aligned Gd/Y superlattice. Odd-numbered peaks arise from magnetic scattering (from Majkizak et al. 1986).

Fig. 35. Neutron scattering data for the Dy/Lu siq)erlattice that develops antiferromagnetic stacking of ferromagnetic Dy blocks, signalled by the peaks marked with arrows.

In order to decide between reentrance or coexistence, Wong et al. (1985a) carried out neutron-diffraction experiments. We recall that because the system is antiferromagnetic, the magnetic and nuclear Bragg peaks are separated in reciprocal (q-) space, and this allows one to study the magnetic order with little... 

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