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 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.
Los Alamos National Laboratory, Los Alamos, NM 87545; mpzslyk@gmail.com.
Yongkang
Y
Luo
Los Alamos National Laboratory, Los Alamos, NM 87545;
F
F
Ronning
Los Alamos National Laboratory, Los Alamos, NM 87545;
N
N
Wakeham
Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China;
Xin
X
Lu
Department of Physics, Sungkyunkwan University, Suwon 440-746, South Korea;
Tuson
T
Park
Department of Physics, Zhejiang University, Hangzhou 310027, China.
Z-A
ZA
Xu
Los Alamos National Laboratory, Los Alamos, NM 87545;
J D
JD
Thompson
Kondo effect; Nozières exhaustion; anomalous Hall effect; heavy Fermion; quantum criticality