Inelastic neutron scattering study of single crystal heavy fermion YbAgGe

TL;DR

This study uses neutron scattering to explore the magnetic properties of YbAgGe, revealing its magnetic ordering, spin fluctuations, and q-dependent dynamics, highlighting its heavy-fermion behavior and potential geometrical frustration effects.

Contribution

First neutron scattering analysis of YbAgGe revealing detailed magnetic ordering and spin fluctuation characteristics in a heavy-fermion compound.

Findings

Magnetic order below 0.5 K with a specific propagation vector

Dominance of quasielastic spin fluctuations with ~1 meV energy

q-dependent spin fluctuation behavior related to geometrical frustration

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.