Specific heat and schottky anomalies of CeP, CeAs, NdP and NdAs

Aeby, A.; Hulliger, F.; Natterer, B.

doi:10.1016/0038-1098(73)90168-3

Cited by 28 publications

(9 citation statements)

References 9 publications

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“…However, these levels can be further split by the exchange field of the moments and/or the internal field of the 3d and 4f moments. 13,14,[27][28][29][30][31] Below 1.8 K, C / T increases logarithmically and tends to saturate at further low temperature at ␥ ϳ 200 mJ/ mol-K 2 . This enhancement might indicate the presence of strong correlations between the Ce ions in the Co-dominated ferromagnetic ground state.…”

Section: Methodsmentioning

confidence: 99%

Interplay betweenCo 3dandCe 4fmagnetism in CeCoAsO

et al. 2010

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We have investigated the ground-state properties of polycrystalline CeCoAsO by means of magnetization, specific heat, and solid-state NMR. Susceptibility and specific-heat measurements suggest a ferromagnetic order at about, T C = 75 K. No further transitions are found down to 0.5 K. At 6.5 K a complex Schottky type of anomaly shows up in the specific-heat results. The interplay between Ce 4f and Co 3d magnetism being responsible for that anomaly is discussed. Furthermore 75 As-NMR investigations have been performed to probe the magnetism on a microscopic scale. As-NMR spectra are analyzed in terms of first and second-order quadrupolar interaction. The anisotropic shift component K ab and K c could be derived from the 75 As powder spectra. Towards lower temperature a strong shift anisotropy was found. Nonetheless K iso tracks the bulk susceptibility down to T = 50 K very well. Furthermore the presence of weak correlations among the Ce ions in the ferromagnetic state is discussed. The observed increase in C / T towards lower temperatures supports this interpretation.

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Section: Methodsmentioning

confidence: 99%

Interplay betweenCo 3dandCe 4fmagnetism in CeCoAsO

et al. 2010

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“…The Ce-O distances are almost the same as the one of CeO 2 , 2.36Å (discrepancy is 0.85%) [48], while the Ce-S2(Ce-As) distance is about 7% (10%) longer than the Ce-S (Ce-As) distance in a rocksalt CeS (CeAs), 2.89Å (3.04Å) [49,50]. These facts suggest that the Ce-O interactions are the same order in both polycrystalline CeOBiS 2 and CeFeAsO, and the Ce-S and Ce-As interactions are relatively weaker than the Ce-O interactions in the view points of the bond length.…”

Section: Comparison With Cefe 4 P 12 and Cerhinmentioning

confidence: 50%

Ce 4f electronic states of CeO1−xFxBiS2 studied by sof

et al. 2017

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“…The partial derivatives @SðTÞ @T ¼ C V ðTÞ T and @UðSðTÞÞ @T ¼ C V ðTÞ are given by Eqs. (17) and (18) for verifying and confirming the derivative (22). To determine the temperature by applying (22) the occupation numbers of the different states must necessarily be given by the occupation numbers (7) and (8) in thermal equilibrium.…”

Section: From the Molar Entropy Capacity To The Molar Entropymentioning

confidence: 99%

“…following Eq. (22). The derivative (34) refers necessarily to the entropy of the internal states with the occupancies of the two level particles x and ð1 À xÞ under perfect mixing conditions, which is fulfilled under thermal equilibrium, only.…”

Section: Entropy S and Internal Energy U In The Non-equilibrium Casementioning

confidence: 99%

“…Since S from (27) and U from (30) are functions of x, not of T, we further have the paradoxical situation that S(U) is attributed values of an internal temperature of a special selection of states, although S and U separately are not known as a function of temperature. Therefore, the temperature defined by (34) cannot be verified experimentally from a temperature dependence of the entropy or internal energy alone like the one defined by (22) in thermal equilibrium.…”

Section: Entropy S and Internal Energy U In The Non-equilibrium Casementioning

confidence: 99%

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Two state particles, mixing entropy and negative temperatures revisited

Hoffmann

2015

Materialwissenschaft Werkst

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The interrelation of thermodynamics and statistical properties of quantum systems can be demonstrated with comparatively little mathematical effort using two state systems (or two state particles). Basic results are summarized for this model system. The entropy can be interpreted as the entropy of mixing particles in their low and high energy state. Thus, an apparent single component system can be considered as a two component system with variable particle numbers. This result has recently been generalized for elementary bosonic and fermionic systems or particles with many different excited states. In this case, one has to take into account as many components as different internal states of the particles are available. The numbers of particles of each component, however, are not constant but depend on the temperature at thermal equilibrium according to statistical principles.In the literature, the concept of negative internal temperatures was previously introduced to characterize and describe special inverted occupation probabilities out of thermal equilibrium. This interpretation of inverted occupation numbers is revisited explicitly for nuclear spin systems. The interpretation of inverted occupancy by negative temperature is based on ignoring athermal contributions to the internal energy due to the inversion procedure. Accordingly, negative temperatures are not justified in the case of systems out of thermal equilibrium but seem to be misleading and confusing. Instead, the different states of the particles represent distinctive components possessing different chemical potentials, magnetic moments or other properties. The present paper intends to remove the confusion about negative temperatures. It shows how processes out of thermal equilibrium are described and understood without difficulties by balancing the different kinds of particles together with their energy and production of entropy within the framework of thermodynamics.

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Specific heat and schottky anomalies of CeP, CeAs, NdP and NdAs

Cited by 28 publications

References 9 publications

Interplay betweenCo 3dandCe 4fmagnetism in CeCoAsO

Interplay betweenCo 3dandCe 4fmagnetism in CeCoAsO

Ce 4f electronic states of CeO1−xFxBiS2 studied by sof

Two state particles, mixing entropy and negative temperatures revisited

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