Atomically thin transition metal dichalcogenides such as 1T'-WS2 showcase remarkable electronic properties, making them prime candidates for future technological applications. A new study published on March 10, 2025, reveals the untapped potential of these materials, particularly when exposed to hydrostatic pressure. Researchers unearth electronic phase transitions, demonstrating how adjusting pressure can induce unusual superconducting states and anomalous Hall effects (AHE) within 1T'-WS2.
The study unveils how increasing hydrostatic pressure enables the manifestation of various electronic phases within this dichalcogenide. At around 1.15 GPa, researchers noted the suppression of conventional superconductivity, accompanied by the emergence of AHE—phenomena typically indicative of altered electronic ground states. Beyond 1.6 GPa, the appearance of what the authors term 'reentrant superconductivity' suggested this material’s complex electronic makeup, where superconductivity competes with the AHE state. This heralded the possibility of distinct pairing symmetry among superconducting electrons.
The authors wrote, “We demonstrate 1T'-WS2 concomitantly transitions to strong topological phases with distinct band orbital characters and Fermi surfaces contributing to superconductivity.” Their findings position 1T'-WS2 as not just any superconductor, but as one where superconductivity, AHE, and band features can be tuned reversibly, adding layers of versatility to its technological promise.
The experimental setup involved fabrications of Hall bar devices made from mechanically exfoliated layers of 1T'-WS2, roughly twelve atomic layers thick. Through careful transport measurements conducted under varying pressure conditions, researchers mapped the superconducting phase diagram. Critical temperature (Tc) plotted against hydrostatic pressure showed intriguing trends; initially, Tc declines with pressure until it vanishes completely at approximately 1.15 GPa, marking the first superconducting state (labelled SC1). Remarkably, another superconducting dome (SC2) emerged at 1.8 GPa, characterized by lower Tc but marking the reentry of superconductivity.
The analysis of magnetic fields revealed significant differences between SC1 and SC2. The parameters defining the upper-critical magnetic fields (bc0Hc2) evaluated for both perpendicular and parallel orientations indicated significant enhancements for SC2 relative to SC1. This demonstrates the varying orchestration of superconducting properties contributed to by changes stemming from hydrostatic adjustments.
The study emphasizes the link between superconductivity profiles and the observed anomalous Hall effect. A notable observation was at pressures above 1.15 GPa, where the anomalous Hall effect sharply increased, indicating altered magnetic properties potentially linked to the underlying mechanisms of superconductivity. These investigations emphasized the influence of different phases, with Hall resistance showcasing typical linear behavior at lower pressures but transitioning to more complex relations as superconductivity emerged and receded with changing pressures.
“These findings position 1T'-WS2 as a tunable superconductor, wherein superconductivity, AHE, and band features can be tuned reversibly,” stressed the researchers. The additional appeal of this study is reinforced by its reversibility; pressure-induced transitions returned samples to their initial behavior upon playbacks, opening the door for future exploratory research on superconductivity mediated by variable room conditions.
To elucidate the underlying electronic structure, the study's researchers employed first-principles calculations of the electronic band structure. They observed how the material experiences topological transitions as they applied pressure. Pressure initially realigned the band structure at 0 GPa, switching to strong topological phase characteristics after surpassing approximately 1 GPa—a significant crossover impacting how electronic charge propagates through the material. This transition marked the genesis of new states potentially facilitating high-temperature superconductivity.
This exploration adds to the burgeoning field of topological superconductors, with claimants understood to extend the fundamental physics isolatable from many-body systems through innovative manipulation of pressures. The complex interplay of electronic states, driven by hydrostatic changes, will offer future avenues of exploration within condensed-matter physics—confirming the fruitful pursuit of advances presented by materials such as 1T'-WS2.
Although many questions remain—particularly around the pairing symmetry mechanisms interacting within the superconducting states—the propensity for reentrant superconductivity and topological character come as future prospects for various applications ranging from quantum computing to energy-efficient electronic devices. The study emphasizes 1T'-WS2's significance as not merely another two-dimensional material but as potentially groundbreaking technology.