Heavy-fermion superconductors serve as a vital playground for exploring unconventional superconductivity and quantum criticality that emerge from the delicate competition between Kondo screening and RKKY magnetic ordering. In recent years, the discovery of two-dimensional van der Waals (vdW) heavy-fermion materials has opened fresh avenues for investigating how reduced dimensionality reshapes strongly correlated electronic states. Among these, CeSiI stands out-its layered crystal structure combined with heavy-fermion behavior makes it an especially attractive platform for studying the interplay among Kondo coherence, antiferromagnetism, and superconductivity.

However, a key question has persisted: can pressure induce superconductivity and quantum criticality exist in such low-dimensional vdW heavy-fermion systems?

Now, a recent study published in Nature Physics provides a definitive answer. Researchers from the Institute of Physics (IOP) at the Chinese Academy of Sciences, using the cubic-anvil high-pressure apparatus developed at the Synergetic Extreme Condition User Facility (SECUF), investigated the transport properties of CeSiI single crystal under pressures up to approximately 11 GPa and at temperatures as low as 50 mK. For the first time, they established the complete temperature–pressure phase diagram of this two-dimensional vdW heavy-fermion system.

Their measurements reveal that antiferromagnetic order is progressively suppressed with increasing pressure, vanishing near 6 GPa—precisely where superconductivity emerges with a dome-shaped phase boundary. Concurrently, the Kondo coherence temperature follows an unusual V-shaped evolution. Detailed low-temperature transport analysis further uncovers non-Fermi-liquid behavior and a pronounced enhancement of quasiparticle effective mass near the critical pressure, pointing to the emergence of unconventional superconductivity mediated by strong quantum critical fluctuations.

Collectively, these results underscore a close relationship among magnetism, Kondo hybridization, quantum criticality, and unconventional superconductivity in a two-dimensional vdW heavy-fermion system. The work establishes CeSiI as a new model platform for studying unconventional superconductivity in reduced dimensions and offers valuable experimental insights into quantum criticality in vdW correlated materials.

Fig. 1. High-pressure transport measurements and temperature-pressure phase diagram of the vdW heavy-fermion meta CeSiI. Increasing pressure suppresses antiferromagnetic order, induces superconductivity near the quantum critical point, and leads to an unusual V-shaped evolution of the Kondo coherence temperature. (Image by Institute of Physics)

Fig. 2. Signatures of quantum criticality in CeSiI. The residual resistivity, transport coefficient, and resistivity exponent all exhibit pronounced anomalies near the critical pressure, consistent with strong quantum critical fluctuations associated with pressure-induced superconductivity. (Image by Institute of Physics)

Contact:

CHENG Jinguang
Institute of Physics
Email：jgcheng@iphy.ac.cn

Keywords:

Heavy-fermion superconductivity; Quantum criticality; van der Waals materials; High pressure; CeSiI

Abstract:

Pressure induces superconductivity in the two-dimensional van der Waals heavy-fermion metal CeSiI, establishing a new platform for studying unconventional superconductivity near an antiferromagnetic quantum critical point in reduced dimensions.