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Spin Correlations in Heavy Fermion Systems
We have used polarized and unpolarized neutron scattering to measure magnetic fluctuations in three heavy fermion systems, CeCu6, U2Zn17, and UPt3, which at low temperatures are paramagnetic, antiferromagnetic, and superconducting, respectively. Our single crystal experiments demonstrate strong antiferromagnetic correlations in both UPt3 and CeCu6. The inelastic spectra are incompatible with both simple Fermi liquid theory and standard models for magnetic excitations in rare earth compounds. However, an effective Hamiltonian which incorporates both single-impurity Kondo properties and antiferromagnetic RKKY interactions, describes our data for both CeCu6 and UPt3 as well as U2Zn17. We show that in accord with recent theoretical work, the RKKY coupling, J, undergoes a significant temperature-dependent renormalization. Indeed, in U2Zn17, it is a rise in J, rather than the single ion susceptibility, which drives the magnetic ordering transition. We note the relation of our results, including the finding of an ordered, antiferromagnetic moment in U0.95Th0.05Pt3, to the unconventional superconductivity of UPt3.
Spin Correlations in Heavy Fermion Systems
We have used polarized and unpolarized neutron scattering to measure magnetic fluctuations in three heavy fermion systems, CeCu6, U2Zn17, and UPt3, which at low temperatures are paramagnetic, antiferromagnetic, and superconducting, respectively. Our single crystal experiments demonstrate strong antiferromagnetic correlations in both UPt3 and CeCu6. The inelastic spectra are incompatible with both simple Fermi liquid theory and standard models for magnetic excitations in rare earth compounds. However, an effective Hamiltonian which incorporates both single-impurity Kondo properties and antiferromagnetic RKKY interactions, describes our data for both CeCu6 and UPt3 as well as U2Zn17. We show that in accord with recent theoretical work, the RKKY coupling, J, undergoes a significant temperature-dependent renormalization. Indeed, in U2Zn17, it is a rise in J, rather than the single ion susceptibility, which drives the magnetic ordering transition. We note the relation of our results, including the finding of an ordered, antiferromagnetic moment in U0.95Th0.05Pt3, to the unconventional superconductivity of UPt3.
Spin Correlations in Heavy Fermion Systems
Gupta, L. C. (Herausgeber:in) / Malik, S. K. (Herausgeber:in) / Aeppli, Gabriel (Autor:in)
Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions ; Kapitel: 32 ; 279-286
01.01.1987
8 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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