ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Specific heat measurements have been performed on four polycrystalline samples of CeAl3 in the temperature range 0.32≤T≤20 K and in magnetic fields H up to 8 T. Though the samples were contaminated by 4–15% of CeAl2 and/or Ce3Al11, the specific heat of CeAl3 is so much larger than that of the other compounds below 1 K that their contribution to the specific heat can be neglected. Normalizing our data by the amount of CeAl3 that we estimated to be present, the specific heats for all four samples are in good qualitative agreement with one another for all T〈1 K and for all the magnetic fields investigated. In this temperature range the specific heat C decreases approximately linearly with increasing H for H〈8 T. It should be noted that Bredl et al. observed a more complex magnetic field dependence in their investigation of the specific heat of CeAl3. The slope of the decrease in C we observed with increasing H in the purest sample is approximately independent of T. In addition the ratio C/T is temperature dependent at low temperatures. All of these properties of the Kondo compound CeAl3 are different from what one would expect on the basis of a simple resonant level model (RLM). For example, RLM predicts that C should decrease with increasing H, but instead of a linear decrease it predicts that C should decrease as H2. A model, which incorporates crystal field effects as well as the Kondo effect, predicts the observed approximately linear magnetic field dependence of the specific heat and also the observed magnetization. In the model the component of the magnetization perpendicular to the c axis is computed by ignoring the Kondo effect and using only the effect of the crystal field splittings. The component of the magnetization parallel to the c axis is computed using RLM to treat the ground state J=±3/2 doublet but also includes contributions from the excited state J=±1/2, ±5/2 doublets which become important at higher fields. The magnetization is found by performing the appropriate average over angles that is required for polycrystalline samples. This magnetization is then used in a thermodynamic relationship for the magnetic field dependence of the specific heat. The generalized form of the RLM predicts the correct magnitude of the decrease in C in an applied field of 8 T.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.335140
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