First observation of superconductivity in a self-intercalated TMD under pressure -Drs. Jiajia Feng, Binbin Yue and Bin Chen

New research led by Drs. Jiajia Feng, Bin Chen, and Binbin Yue at the Center for High Pressure Science and Technology Advanced Research (HPSTAR) has, for the first time, realized a superconducting state in the self-intercalated transition metal dichalcogenide (TMD) V_1/4VS₂ through high-pressure tuning. This achievement fills a significant gap in the study of pressure-induced superconductivity in this class of materials. Published in Physical Review Letters, the findings demonstrate that self-intercalated TMDs offer an ideal platform for investigating pressure-induced quantum critical points, electronic topological transitions, and superconductivity, opening new avenues for exploring exotic quantum states and uncovering novel high-pressure physical phenomena.

Transition metal dichalcogenides are a class of highly valuable 2D quantum materials. Intercalating metal atoms can introduce rich quantum critical states, making them a hotspot in condensed matter physics. Among these, self-intercalation of magnetic atoms (intrinsic magnetic atoms embedded between layers) represents an innovative approach to material tuning. Due to the chemical similarity between intercalated atoms and the host lattice, this method enables precise modulation of electronic and spin states while minimizing lattice distortion and maintaining structural stability. Therefore, it is an ideal system for studying strongly correlated physics under extreme conditions.

V_1/4VS₂ (also known as V₅S₈) is a representative self-intercalated TMD. The interlayer vanadium atoms carry localized magnetic moments, giving the material an antiferromagnetic ground state, while the in-plane vanadium electrons are delocalized, imparting metallicity. This natural combination of antiferromagnetism and metallicity makes it an excellent candidate for studying the interplay between magnetism and superconductivity. Previous attempts to modify its antiferromagnetic properties via exfoliation or gate tuning yielded limited success in inducing superconductivity.

Pressure, as a key thermodynamic parameter, can effectively, continuously, and intrinsically modulate the electronic structure and magnetic characteristics of materials. It is widely used to control quantum phase transitions in strongly correlated systems. To explore the quantum state evolution of V_1/4VS₂ under high pressure, the team first synthesized high-purity V_1/4VS₂ crystals using chemical vapor transport. They then employed a combination of high-pressure electrical transport measurements, in-situ synchrotron X-ray diffraction, and first-principles calculations to systematically investigate the material under pressure.

The study clearly revealed, for the first time, the full physical evolution from an antiferromagnetic state to a quantum critical point, ultimately leading to a superconducting state. Experimentally, as pressure gradually increased, the lattice of V_1/4VS₂ compressed continuously, and the localized 3d electrons of interlayer vanadium began to delocalize. The antiferromagnetic order was progressively suppressed. At 9 GPa, antiferromagnetic signals disappeared entirely, exhibiting typical non-Fermi liquid behavior. With further pressure increase, electrons became fully delocalized, enhancing metallicity. Beyond 60 GPa, the Fermi surface underwent a complete topological reconstruction (Lifshitz transition), electron-phonon coupling was significantly enhanced, and the material became superconducting, marking the critical transition from an antiferromagnetic metal to a superconductor. The superconducting state remained stable up to the maximum experimental pressure (~100 GPa).

Caption: Transition of V_1/4VS₂ from an antiferromagnetic non-Fermi liquid to a superconducting Fermi liquid under high pressure.

Remarkably, throughout the high-pressure experiments, V_1/4VS₂ retained a stable monoclinic crystal structure, experiencing only continuous lattice compression without any structural phase transition. Researcher Yue Binbin noted, “This indicates that the superconducting transition in V_1/4VS₂ is purely driven by an electronic topological transition. The pressure-induced Fermi surface reconstruction creates conditions for effective electron pairing, ultimately inducing superconductivity.” The study also mapped a new pressure-induced superconducting phase diagram for 2D materials.” Co-corresponding author Dr. Feng Jiajia added. “Unlike the widely reported mechanism where superconductivity emerges directly from a magnetic quantum critical point, V_1/4VS₂ superconductivity is decoupled from the magnetic quantum critical point, driven jointly by Fermi surface reconstruction and electronic topological transitions. This discovery provides a new phase diagram for studying pressure-induced superconductivity in 2D materials and enriches our understanding of the high-pressure superconducting mechanisms in 2D quantum materials.”

The co-first authors of this work are PhD student Miao Jingwei and postdoctoral researcher Dr. Feng Jiajia. The corresponding authors are Researchers Yue Binbin, Chen Bin, and Dr. Feng Jiajia. The work was supported by the Shanghai Synchrotron Radiation Facility BL15U, Japan’s SPring-8 BL10XU beamline, and the National Natural Science Foundation of China.

北京高压科学研究中心的陈斌研究员、岳彬彬研究员带领的研究团队在自插层过渡金属二硫族化合物V_1/4VS₂的研究中，通过高压调控首次实现了自插层过渡金属二硫族化合物超导态，填补了该类材料压致超导研究的空白。相关研究以“Antiferromagnetic Quantum Critical Point and Superconductivity in Self-Intercalated TMD V_1/4VS₂ under High Pressure” 为题发表于Physical Review Letters。该研究结果表明，自插层过渡金属二硫族化合物是探索压力诱导量子临界点、电子拓扑转变及超导性的理想体系，为寻找该类材料中的奇异量子态、解析其高压下的新物理规律开辟了新的研究路径。