Kondo effect and quadrupolar interactions in single-crystal CePd2Al3

✍ Scribed by S.A.M. Mentink; N.M. Bos; G.J. Nieuwenhuys; A. Drost; E. Frikkee; L.T. Tai; A.A. Menovsky; J.A. Mydosh

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 232 KB
• Volume: 186-188
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(93)90603-4

✦ Synopsis

We have studied the magnetic anisotropy on a single crystal of the new heavy-fermion compound CePd2AI 3. The magnetic moments lie in the hexagonal (a, b)-plane, but do not order antiferromagnetically, in contrast to annealed polycrystalline samples. The Kondo effect can account for the large specific heat at low temperatures. The small crystal-field splitting causes a field-induced electric-quadrupole moment, which orders in fields larger than 4.3 T.

The new heavy-fermion (HF) compounds, crystallizing in the hexagonal PrNi2A13 structure, exhibit a strong magnetocrystalline anisotropy. In the HF superconductor UPd2A13, large uranium moments of 0.85~R are coupled feromagnetically in the (a, b)plane with an antiferromagnetic stacking along the c-axis [1-3]. We have prepared single-crystalline samples of the cerium homolog CePdeA13, and observe a similar magnetic anisotropy. However, the annealed single-crystal sample does not display the long-range antiferromagnetic order as was previously observed in annealed polycrystalline samples [4,5]. Here we present specific-heat, resistivity and susceptibility measurements (down to 1.3 K) and neutron-diffraction data (to 1.7K) on single-crystal CePd2AI 3 to study its magnetic anisotropy. Furthermore, we will discuss the striking differences with the polycrystalline samples and offer the first evidence for the occurrence of field-induced first-order transitions, which are due to the small crystal-field splitting as deduced from our experiments.

The single crystal was grown at the FOM-ALMOS facility with the 'tri-arc' Czochralski method, using a 2%-excess of aluminum. The resulting large single crystal exhibited strains, which lead us to anneal the crystal at 1000°C for 1 week in argon-filled quartz ampules. The relative concentrations as determined by electron probe microanalysis (EPMA) with modern