Pressure and field dependent studies of single-crystalline YbCu4In

Hauser, Robert G.; Naber, L.; Schaudy, G.; Bauer, E.; Hilscher, G.; Kindler, B.; Aßmus, W.

doi:10.1007/bf02570258

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…We observed a distinct peak in the heat capacity at the same temperature where susceptibility exhibits a large jump. A very similar behaviour has been observed in the heat capacity of polycrystalline YbInCu 4 [29,30]. On the other hand, the heat capacity of YbInCu 4 single crystals exhibits a first-order type anomaly at T V along with a jump in the entropy of 10 J mol −1 K −1 [31].…”

Section: Resultssupporting

confidence: 76%

A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

Adroja¹,

Echizen²,

Takabatake³

et al. 1999

J. Phys.: Condens. Matter

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The first-order valence transition in has been investigated for single crystalline samples with x = 0.32 and x = 0.35 as well as for polycrystalline samples with (x varied in steps of 0.01) through the measurements of magnetic susceptibility, . For the single crystal with x = 0.32, exhibits a strong anisotropic mixed-valence behaviour. On the other hand, of the crystal with x = 0.35 exhibits a sharp first-order valence transition at 50 K. In both crystals, the strong anisotropy, , is maintained as in the host compound CeNiSn. The arc-melted polycrystalline alloys with a narrow range of Co composition, x = 0.33-0.37, show a sharp drop in below 70 K and large hysteresis. This transition becomes sharper by annealing at . For the optimum concentration x = 0.35, the drop in at the transition becomes as high as 72% for the single crystal and 69% for the polycrystalline alloy for which a jump in ac heat capacity was observed at 55 K. Analysis of the above results reveals that the phase transition involves a large change in the Kondo temperature . The small volume discontinuity at the transition suggests that the phase transition is not due to a Kondo volume collapse. A possible mechanism responsible for the phase transition in the present alloys is proposed.

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Section: Resultssupporting

confidence: 76%

A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

Adroja¹,

Echizen²,

Takabatake³

et al. 1999

J. Phys.: Condens. Matter

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“…Parameters K for the present compounds estimated from the experimental values of C v are listed in table 1, where common values of κ = 10 −6 bar −1 [19,24,34,40], V m = 55 cm 3 , C = 2.6 emu K mol −1 (the Yb 3+ free-ion value) and appropriate values of T K (listed in table 1) were used. Similar values have been estimated from other experimental results [10,14,19,24,25,41,42]. These values are large in magnitude and comparable with those for typical Ce-based Kondo or heavy-fermion compounds although the sign is opposite [37], indicating the strong volume dependence of T K .…”

Section: The Interconfigurational Fluctuation Modelsupporting

confidence: 89%

Magnetostriction of ytterbium-based Kondo compounds YbXCu₄(X = In, Ag and Au)

Sokolov

Nakamura

Shiga

1999

J. Phys.: Condens. Matter

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Magnetostrictions were measured for polycrystalline YbXCu4 (X = In, Ag and Au) by the three-terminal capacitance method up to the magnetic field of 8 T in the temperature range 5-100 K. The volume magnetostrictions of all of the compounds are negative in contrast to the case for Ce-based Kondo systems. The absolute values of the volume magnetostriction coefficient for YbInCu4 and YbAgCu4 are large at low temperatures but depressed in the high-temperature localized-moment regime, whereas those of YbAuCu4 with almost stable Yb3+ moments are small. The results are discussed in terms of a modified Kondo-lattice model, where we emphasize that the volume dependence of the effective 4f electron (hole) number plays a dominant role. The anisotropic magnetostrictions of YbAuCu4 and YbAgCu4 have a positive sign but that of YbInCu4 is negative, suggesting a difference in background crystal-field ground states of the Yb3+ multiplet.

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“…Many other groups have also reported similar values for dT v /dP. 1, 15,16,19,20 In many mixed-valence materials where Kondo effects are dominant, there are additional relationships among derivatives of the free energy, beyond those required by basic thermodynamics, that are found because of an experimentally observed scaling of the free energy. 21 Explicitly, if F ϭF N (T,V)ϩF e (T,V), i.e., the free energy is composed of a ''normal'' contribution F N and an electronic contribution F e , which can be written as…”

mentioning

confidence: 77%

“…We know of two previous reports of specific-heat measurements through the valence transition in YbInCu 4 . 1, 15 Hauser et al report an essentially linear increase of entropy from ϳ3 J/mol K at 40 K to ϳ11 J/mol K at 70 K. Felner et al observe a two-peak structure ͑at ϳ40 K and ϳ60 K) in specific heat that leads to an integrated entropy of 13.3 J/mol K at 70 K. These three measurements yield similar entropy changes through the transition range. The differences can be ascribed to stoichiometric variations throughout the sample leading to broadened transitions.…”

mentioning

confidence: 95%

Thermodynamics of the first-order valence transition inYbInCu4

Sarrao

Ramirez²,

Darling

et al. 1998

Phys. Rev. B

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We present measurements of the specific heat and complete elastic moduli of YbInCu 4 as a function of temperature in order to complement existing thermal expansion data. Together these data allow a complete analysis of the thermodynamics of the first-order isostructural valence transition in YbInCu 4. The Clausius-Clapeyron equation predicts well the measured pressure dependence of the valence transition temperature. Estimates of the Gruneisen parameter from thermodynamic measurements and from pressure-dependent magnetic susceptibility in both the high-temperature and low-temperature phases of YbInCu 4 are in good agreement. On the other hand, a Gruneisen analysis of the change in Kondo temperature at the valence transition fails, emphasizing the importance of carrier-density changes associated with the valence transition, unlike in the case of the ␥-␣ transition in elemental Ce. Finally, we address the issue of precursive rounding in the elastic moduli for temperatures greater than the valence transition temperature and argue that thermodynamically YbInCu 4 's valence transition is indeed first order.

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Pressure and field dependent studies of single-crystalline YbCu4In

Cited by 6 publications

References 7 publications

A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

Magnetostriction of ytterbium-based Kondo compounds YbXCu₄(X = In, Ag and Au)

Thermodynamics of the first-order valence transition inYbInCu4

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Pressure and field dependent studies of single-crystalline YbCu4In

Cited by 6 publications

References 7 publications

A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

A study of the first-order valence transition in single crystals by magnetic susceptibility measurements

Magnetostriction of ytterbium-based Kondo compounds YbXCu4(X = In, Ag and Au)

Thermodynamics of the first-order valence transition inYbInCu4

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Magnetostriction of ytterbium-based Kondo compounds YbXCu₄(X = In, Ag and Au)