Physical properties of the Ce2MAl7Ge4 heavy-fermion compounds (M=Co,Ir,Ni,Pd)

N. J. Ghimire, S. K. Cary, S. Eley, N. A. Wakeham, P. F.S. Rosa, T. Albrecht-Schmitt, Y. Lee, M. Janoschek, C. M. Brown, L. Civale, J. D. Thompson, F. Ronning, E. D. Bauer

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

We report the synthesis, crystal structure, and characterization by means of single-crystal x-ray diffraction, neutron powder diffraction, and magnetic, thermal, and transport measurements of the new heavy-fermion compounds Ce2MAl7Ge4 (M=Co,Ir,Ni,Pd). These compounds crystallize in a noncentrosymmetric tetragonal space group P421m, consisting of layers of square nets of Ce atoms separated by Ge-Al and M-Al-Ge blocks. Ce2CoAl7Ge4,Ce2IrAl7Ge4, and Ce2NiAl7Ge4 order magnetically below TM=1.8, 1.6, and 0.8 K, respectively. There is no evidence of magnetic ordering in Ce2PdAl7Ge4 down to 0.4 K. The small amount of entropy released in the magnetic state of Ce2MAl7Ge4 (M = Co, Ir, Ni) and the reduced specific heat jump at TM suggest a strong Kondo interaction in these materials. Ce2PdAl7Ge4 shows non-Fermi liquid behavior, possibly due to the presence of a nearby quantum critical point.

Original languageEnglish
Article number205141
JournalPhysical Review B
Volume93
Issue number20
DOIs
StatePublished - May 23 2016
Externally publishedYes

Funding

We thank Z. Fisk, J. Lawrence, and A. Mar for stimulating discussion. Work at Los Alamos National Laboratory was performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. The EDS measurements were performed at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. DE-AC52-06NA25396. P.F.S.R. acknowledges a Director's Postdoctoral Fellowship supported through the Los Alamos LDRD program. Support for T.E.A.S. and S.K.C. was provided by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, Heavy Elements Chemistry Program, U.S. Department of Energy, under Grant No. DE-FG02-13ER16414. Y.L. was supported by the Institute of Basic Sciences (IBS), Grant No. IBS-R014-D1. We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work.

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