Pressure-tuned quantum criticality in the antiferromagnetic Kondo semimetal CeNi2−δAs2

The easily tuned balance among competing interactions in Kondo-lattice metals allows access to a zero-temperature, continuous transition between magnetically ordered and disordered phases, a quantum-critical point (QCP). Indeed, these highly correlated electron materials are prototypes for discoveri...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2015-11, Vol.112 (44), p.13520-13524
Main Authors: Luo, Yongkang, Ronning, F, Wakeham, N, Lu, Xin, Park, Tuson, Xu, Z-A, Thompson, J D
Format: Article
Language:English
Subjects:
anomalous Hall effect
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
heavy Fermion
Kondo effect
MATERIALS SCIENCE
Nozieres exhaustion
Physical Sciences
quantum criticality
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Summary:The easily tuned balance among competing interactions in Kondo-lattice metals allows access to a zero-temperature, continuous transition between magnetically ordered and disordered phases, a quantum-critical point (QCP). Indeed, these highly correlated electron materials are prototypes for discovering and exploring quantum-critical states. Theoretical models proposed to account for the strange thermodynamic and electrical transport properties that emerge around the QCP of a Kondo lattice assume the presence of an indefinitely large number of itinerant charge carriers. Here, we report a systematic transport and thermodynamic investigation of the Kondo-lattice system CeNi2-δAs2 (δ ≈ 0.28) as its antiferromagnetic order is tuned by pressure and magnetic field to zero-temperature boundaries. These experiments show that the very small but finite carrier density of ~0.032 E-/formular unit in CeNi2-δAs2 leads to unexpected transport signatures of quantum criticality and the delayed development of a fully coherent Kondo-lattice state with decreasing temperature. The small carrier density and associated semimetallicity of this Kondo-lattice material favor an unconventional, local-moment type of quantum criticality and raises the specter of the Nozières exhaustion idea that an insufficient number of conduction-electron spins to separately screen local moments requires collective Kondo screening.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1509581112