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Inelastic neutron scattering study of single crystal heavy fermion YbAgGe

B. Fak·D. F. McMorrow·P. G. Niklowitz·S. Raymond·E. Ressouche·J. Flouquet·P. C. Canfield·S. L. Bud'ko·Y. Janssen·M. J. Gutmann
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Abstract

Single crystals of the heavy-fermion compound YbAgGe have been studied by neutron scattering. The magnetic ordering occurring below T1=0.5 K is characterized by a commensurate propagation vector k=(1/3,0,1/3) and the moments in the basal plane of the hexagonal structure. The dynamic magnetic susceptibility is dominated by quasielastic spin fluctuations with a characteristic energy Gamma of the order of 1 meV. The spins fluctuate predominantly in the basal plane. No spin-wave excitations are observed in the magnetically ordered phase. Below the Kondo temperature, TK=20 K, Gamma shows a strong q dependence for wave vectors along the c* direction, but is q-independent in the basal plane. Gamma shows initially a rapid increase with temperature T at the antiferromagnetic zone center, but follows a standard sqrt(T) law for other q values and for T>TK in general. These observations classify YbAgGe as a well-behaved heavy-fermion compound with a particular q-dependence of the antiferromagnetic spin fluctuations, possibly related to the geometrical frustration of the Yb3+ ions.

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B. Fak, D. F. McMorrow, P. G. Niklowitz, S. Raymond, E. Ressouche, J. Flouquet, P. C. Canfield, S. L. Bud'ko, Y. Janssen, M. J. Gutmann. 2004-10-28. Inelastic neutron scattering study of single crystal heavy fermion YbAgGe. https://doi.org/10.1088/0953-8984%2F17%2F2%2F006

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