Heavy-fermion quantum criticality and destruction of the Kondo effect in a nickel oxypnictide

• Published in: Nature materials 2014-08, Vol.13 (8), p.777-781
• Main Authors: Luo, Yongkang, Pourovskii, Leonid, Rowley, S. E., Li, Yuke, Feng, Chunmu, Georges, Antoine, Dai, Jianhui, Cao, Guanghan, Xu, Zhu’an, Si, Qimiao, Ong, N. P.
• Format: Article
• Language: English
• Subjects: 639/301/119; Biomaterials; Condensed Matter Physics; High temperature; Intermetallic compounds; letter; Low temperature; Magnetism; Materials Science; Nanotechnology; Nickel; Optical and Electronic Materials; Quantum physics
• ISSN: 1476-1122; 1476-4660; 1476-4660
• DOI: 10.1038/nmat3991

Transitions between stable quantum phases of matter typically involve going through an unstable quantum critical point, the unique properties of which have become a focus of research in the past decade or so. Extensive bulk measurements on the nickel oxypnictide system CeNiAsO uncover heavy-fermion behaviour, suggesting the family of oxipnictides may be ideal materials for examining quantum criticality more broadly. A quantum critical point arises at a continuous transformation between distinct phases of matter at zero temperature. Studies in antiferromagnetic heavy-fermion materials have revealed that quantum criticality has several classes, with an unconventional type that involves a critical destruction of the Kondo entanglement 1 , 2 . To understand such varieties, it is important to extend the materials basis beyond the usual setting of intermetallic compounds. Here we show that a nickel oxypnictide, CeNiAsO, exhibits a heavy-fermion antiferromagnetic quantum critical point as a function of either pressure or P/As substitution. At the quantum critical point, non-Fermi-liquid behaviour appears, which is accompanied by a divergent effective carrier mass. Across the quantum critical point, the low-temperature Hall coefficient undergoes a rapid sign change, suggesting a sudden jump of the Fermi surface and a destruction of the Kondo effect 3 , 4 . Our results imply that the enormous materials basis for the oxypnictides, which has been so crucial in the search for high-temperature superconductivity, will also play a vital role in the effort to establish the universality classes of quantum criticality in strongly correlated electron systems.