Reduced moment magnetic ordering in a Kondo lattice compound: Ce8Pd24Ga

Abstract

The magnetic ground state of the antiferromagnet Kondo lattice compound Ce 8 Pd 24 Ga has been investigated using neutron powder diffraction, inelastic neutron scattering and zero-field muon spin relaxation measurements. The neutron diffraction analysis, below T N (3.6 0.2K), reveals a commensurate type-C antiferromagnetic structure with the ordered state magnetic moment of ~0.36 B /Ce-atom along the cubic <111> direction. The analysis of the inelastic neutron scattering (INS) data based on the crystal field (CF) model reveals a doublet ground state with a ground state moment of 1.29 B/Ce-atom. The observed magnetic moment from neutron diffraction, which is small compared to the expected value from CF-analysis, is attributed to screening of the local Ce moment by the Kondo effect. This is supported by the observed Kondo-type resistivity and a small change in the entropy of Ce 8 Pd 24 Ga at T N . The zero-field muon spin relaxation rate exhibits a sharp increase below T N indicating ordering of Ce moments, in agreement with the neutron diffraction data. The present studies reveal that the physical properties of Ce 8 Pd 24 Ga are governed by the onsite Kondo compensation, the moment stabilizing intersite RKKY interaction and the crystal field effect.

Magnetic order and crystalline electric field excitations of the quantum critical heavy-fermion ferromagnet CeRh6Ge4

“…To determine the splitting of the J = 5/2 Ce ground-state multiplet of CeRh 6 Ge 4 by crystalline electric fields (CEFs), the single crystal magnetic susceptibility [17] 2 ground state is anticipated, since this is the only eigenstate which corresponds to a nonzero in-plane moment, with μ x = ψ ∓ |g J (J + + J − )/2|ψ ± = 1.28μ B /Ce. Since μ x is much larger than the observed low-temperature moment of around 0.2 − 0.3μ B /Ce, this indicates that there is a reduced ordered moment, either due to Kondo screening processes or significant zero-point fluctuations [17,33]. From the large positive value of B 0 2 , the ab plane is expected to correspond to the easy direction of magnetization, in line with the observed high-and low-temperature susceptibilities.…”

Evolution of quantum criticality in the system CeNi9Ge4

“…The absence of any sign of coherent frequency oscillations in the zero field µSR spectra which has been observed also in some other antiferromagnetic materials, e.g. Ce 8 Pd 24 Ga [19], refers to a muon stopping site in a high symmetry position with respect to the Ce sublattice where dipolar fields of AF 3b and 3d refers a muon spin depolarization by dynamically fluctuating dipolar fields. In the case of CeNi 9 Ge 4 a clean simple exponential behaviour A(t) ∝ exp (−λt) with a depolarization rate λ = 0.133 µs −1 at 35 mK is observed (see figure 3b).…”

A reduced moment antiferromagnetic Kondo lattice compound: Ce8Pd24Ga

“…The present neutron diffraction study of Ce 8 Pd 24 Ga shows that the Ce magnetic moment in the ordered state is B0.36 m B /Ce-atom, compared with the predicted moment 1.29 m B /Ce-atom from the crystal field ground state [5], which clearly indicates the reduced moment antiferromagnetic ordering. The presence of the Kondo effect in Ce 8 Pd 24 Ga has been confirmed through determination of the temperature dependent resistivity, of the scaling behaviour of the magnetoresistance, and of the observed small entropy change at T N compared with Rln(2), expected from a doublet CF ground state [2,4].…”