Crystal-field excitations in the heavy-fermion alloys CeCu6−x Au x studied by specific heat and inelastic neutron scattering

Stroka, B.; Schröder, A.; Trappmann, T.; Löhneysen, H. v.; Loewenhaupt, M.; Severing, A.

doi:10.1007/bf02198148

Cited by 24 publications

(24 citation statements)

References 16 publications

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“…The conductivity is given by the Drude result σ ⊥ = e 2 nτ /m with, however, the proper relaxation time τ changed by the gap according to Eq. (7). This yields a relative change of the resistivity ρ ⊥ induced by the magnetic order, which is in leading order in ∆ δρ (2)…”

Section: Interplay Of Magnetic Order and Transportmentioning

confidence: 97%

“…It has been known for a decade that the heavy-fermion compound CeCu 6 which does not show magnetic order down to temperatures T of at least 5 mK [2,3] exhibits long-range antiferromagnetic order when alloyed with Au or Ag [4,5]. From the beginning, this has been explained [6] as arising from the interplay between onsite Kondo screening of the Ce magnetic moments in a crystal-field split 2 F 5/2 doublet groundstate [7] and the RKKY interaction between Ce moments. The latter is favored by a weakening of the Kondo screening with increasing of the interatomic spacing upon alloying with Au.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic order and transport in the heavy-fermion system CeCu Au

et al. 1998

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We report on extensive elastic neutron scattering to determine the wave vector of the magnetic order in CeCu6−xAux single crystals for x > 0.1. For all values of x investigated (0.2, 0.3, 0.5, 1.0) we find long-range incommensurate antiferromagnetic order with an ordering vector Q ≈ (0.625 0 0.275) for x = 0.2, nearly unchanged for x = 0.3, and Q ≈ (0.59 0 0) for x = 0.5, staying roughly the same for x = 1.0. In addition, short-range correlations are observed at x = 0.2, reminiscent of those found previously for x = 0.1. The ordered magnetic moment is found to increase rapidly for small x, and more slowly for the larger x values. The increase of the specific-heat anomaly at the ordering temperature with x is in qualitative accord with this behavior. Finally, data of the electrical resistivity for current flow along the three crystallographic directions are presented, showing a clear signature of the magnetic order. A theoretical interpretation of the interplay of magnetic order and transport in terms of (i) the partial suppression of the Kondo effect by the staggered magnetization and (ii) the anisotropic band structure induced by the staggered field is shown to account well for the data, provided the ordering vector Q is close to 2kF , where kF is a typical Fermi momentum.PACS. 75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena -75.25.+z Spin arrangements in magnetically ordered materials -72.15.Eb Electrical and thermal conduction in crystalline metals and alloys

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Section: Interplay Of Magnetic Order and Transportmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Magnetic order and transport in the heavy-fermion system CeCu Au

et al. 1998

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“…In( TITO) [2] is observed between 0.06K and 2K, a T range considerably larger than one decade. The upturn above 2K is due to the onset of crystal-field excitations[27] and to the phonon contribution which was not subtracted from the data. The coefficients are a = -0.578 J/molK2 and TO = 6.18 K in good agreement with previous data[2].…”

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Thermodynamic properties of CeCu_6‐xAu_x: Fermi‐liquid vs. non‐Fermi‐liquid behaviour

et al. 1996

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We report on a detailed comparison of the thermodynamic properties of the heavy-fermion system CeCu6 which can be described as a Fermi liquid at low temperatures T < 0.1 K, and CeCus.9Auo.l where strong deviations from the Fermi-liquid behaviour were found previously in the T dependence of the specific heat C , magnetization M and electrical resistivity p. The specific heat, magnetization and elastic constants are investigated in a large range of magnetic fields, corroborating the idea that the non-Fermi-liquid behaviour arises from low-lying spin excitations. For the elastic constants, a striking linear T dependence is found for CeCus 9Auo I in contrast to the T2 Fermiliquid behaviour of CeCus.

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“…We also plan to examine samples in which one Cu site is substituted with Au. This weakens the Kondo interaction and sharpens the CF levels [3]. …”

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confidence: 97%

“…A number of investigations of the CF level scheme in the heavy fermion compound CeCu 6 have been made. These include inelastic neutron scattering (INS) measurements [1][2][3]. These measurements proposed different CF level transitions.…”

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Spin-resolved neutron spectroscopy from the heavy Fermion compound CeCu6

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et al. 2004

Physica B: Condensed Matter

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Neutron time-of-flight spectroscopy with neutron polarisation analysis permits the in situ separation of magnetic and lattice vibrational energy spectra. Preliminary experiments on the heavy Fermion compound, CeCu 6 ; in which the Ce magnetic moment is suppressed by the Kondo effect, allow an indicative separation of a broadened crystal field transition and features due to lattice vibrations. An inelastic spin-flip feature at À12 meV is due to the crystal field while an inelastic non-spin-flip feature at À6 meV is predominantly due to phonon scattering. r

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Crystal-field excitations in the heavy-fermion alloys CeCu6−x Au x studied by specific heat and inelastic neutron scattering

Cited by 24 publications

References 16 publications

Magnetic order and transport in the heavy-fermion system CeCu Au

Magnetic order and transport in the heavy-fermion system CeCu Au

Thermodynamic properties of CeCu_6‐xAu_x: Fermi‐liquid vs. non‐Fermi‐liquid behaviour

Spin-resolved neutron spectroscopy from the heavy Fermion compound CeCu6

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Crystal-field excitations in the heavy-fermion alloys CeCu6−x Au x studied by specific heat and inelastic neutron scattering

Cited by 24 publications

References 16 publications

Magnetic order and transport in the heavy-fermion system CeCu Au

Magnetic order and transport in the heavy-fermion system CeCu Au

Thermodynamic properties of CeCu6‐xAux: Fermi‐liquid vs. non‐Fermi‐liquid behaviour

Spin-resolved neutron spectroscopy from the heavy Fermion compound CeCu6

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Thermodynamic properties of CeCu_6‐xAu_x: Fermi‐liquid vs. non‐Fermi‐liquid behaviour