Pressure realized record performance in ising superconductor- Dr. Wenge Yang

New research from a team of scientists led by Dr. Wenge Yang from the Center for High Pressure Science and Technology Advanced Research, in collaboration with Dr. Ping Cui from University of Science and Technology of China, have achieved record-breaking performance in the Ising superconductor 4Hb-TaS₂ through pressure tuning. The in-plane upper critical field of the pressure-optimized 4Hb-TaS₂ rivals that of trilayer TaS₂, while its superconducting transition temperature (Tc) sets the highest benchmark among all TaS₂-based weak-interlayer-coupling systems reported to date. This work was published in NPJ Quantum Materials under the title“Enhanced Ising superconductivity in a unicompositional bulk 4Hb-TaS₂ superlattice via pressure.”

Ising superconductors have attracted great attention for their in-plane upper critical fields far exceeding the Pauli limit, making them promising candidates for high-field superconducting devices. Previous studies have focused primarily on two-dimensional limit systems or bulk materials with molecular intercalation, which often suffer from sample degradation and limited tunability, hindering practical applications. Traditional approaches largely rely on changing material thickness or constructing heterostructures, while intercalation introduces compositional complexity and stability issues. Achieving optimized Ising superconductivity in a single-component, stable bulk material has therefore remained a key challenge.

The team applied high pressure to systematically tune the physical properties of 4Hb-TaS₂, a unique layered material composed of alternating superconducting 1H-TaS₂ layers and Mott-insulating 1T-TaS₂ layers with a centrosymmetric structure. Using a combination of in situ high-pressure X-ray diffraction, Hall-effect measurements, and first-principles calculations, they found that at even moderate pressure (up to 1.2 GPa), the superconducting transition temperature of 4Hb-TaS₂ increases from 3.8 K at ambient pressure to 5 K—the highest T_c reported for weakly coupled TaS₂ systems. Moreover, the in-plane upper critical field reaches approximately 25 T at 0.8 GPa, approaching the performance of trilayer TaS₂ and exceeding the Pauli limit by more than threefold.

Further analysis revealed that under pressure, the interlayer coupling and spin-orbit coupling in 4Hb-TaS₂ act synergistically while simultaneously suppressing the charge-density-wave (CDW) order, collectively producing a “dome-shaped” enhancement of superconducting performance. Importantly, the crystal structure of 4Hb-TaS₂ remains stable throughout compression, and its single-component nature avoids the compositional complexity of intercalated materials, highlighting its practical application potential.

Unlike traditional approaches that tune superconductivity by changing layer number, this study demonstrates that high pressure can serve as an effective tuning parameter, revealing the critical roles of CDW order, interlayer coupling, and spin-orbit coupling in controlling superconductivity in Ising systems. These findings provide key experimental insights into the underlying mechanisms of Ising superconductivity. They also suggest that high-pressure techniques can not only optimize existing superconductors but also offer a new pathway to discover high-performance Ising superconductors, paving the way for applications in high-field, low-energy superconducting devices.

Caption: Mechanism and phase diagram of high-pressure tuning of superconducting transition temperature and upper critical field in 4Hb-TaS₂.

北京高压科学研究中心的杨文革团队与中国科学技术大学的崔萍团队等合作，通过高压调控的方法，在伊辛超导体材料 4Hb-TaS₂ 中实现了创纪录的性能提升。高压优化后的 4Hb-TaS₂ 伊辛超导体，其面内上临界磁场可与三层 TaS₂ 相媲美，同时其超导转变温度也创下了基于TaS₂弱耦合系统的最高纪录。相关研究发表于 NPJ Quantum Materials。