Pressure-induced double-dome superconductivity in doped kagome metal Cs(V0.86Ta0.14)3Sb5 without charge density wave

The gist The study reports high-pressure resistance measurements on Ta-doped Cs(V0.86Ta0.14)3Sb5 to check whether double-dome superconductivity still exists when there is no CDW order, revealing two superconducting domes under pressure in the T−P phase diagram, which reinforces the notion that double-dome superconductivity is an intrinsic and universal feature of the AV3Sb5 family even in the complete absence of long-range CDW

Pressure Effects on Superconductivity

The researchers performed high-pressure resistance measurements on Cs(V0.86Ta0.14)3Sb5 up to 48 GPa to check for the existence of double-dome superconductivity without CDW order <ref:2610.12257#pg5>. Two superconducting domes are clearly revealed in the T−P phase diagram, which reinforces the notion that double-dome superconductivity is an intrinsic and universal feature of the AV3Sb5 family even in the complete absence of long-range CDW <ref:2610.12257#pg5>. The non-monotonic evolution of Tc at low pressures contrasts with the “M-shaped” dome in the parent CsV3Sb5 <ref:2610.12257#pg5>.

Evolution of Superconducting Dome Structure

The superconducting transition temperature, Tc, initially drops slightly from 5.29 K at ambient pressure to 4.90 K at 0.33 GPa, before increasing to a maximum of 5.70 K at 0.61 GPa <ref:2610.12257#pg4>. Upon further compression, Tc decreases continuously to 0.98 K at 12.3 GPa <ref:2610.12257#pg5>. At higher pressures, Tc rises again, reaching 4.46 K at 47.7 GPa <ref:2610.12257#pg4>. This evolution of Tc establishes two superconducting domes under pressure, which are similar to those in CsV3Sb5 <ref:2610.12257#pg2>. The first superconducting dome (below 10 GPa) is widely attributed to the competition between CDW and SC <ref:2610.12257#pg3>.

Underlying Physics of Double-Dome Superconductivity

The second dome is likely associated with the dimensional crossover induced by pressure <ref:2610.12257#pg5>. The first dome may also correlate to a pressure-induced shift of the VHS relative to the Fermi level, as seen in CsV2.6Ta0.4Sb5 where the VHS around the M point coincides with the Fermi level. Furthermore, it is proposed that a recent theoretical study suggests that soft loop-current fluctuations in kagome metals drive a transition of SC from an s± state (low-pressure SC-I) to a chiral d + i d state (high-pressure SC-II) <ref:2610.12257#pg5>.

Comparison with Doped Variants

The non-monotonic low-pressure behavior in the Ta-doped sample distinctly differs from that of the Ti-doped CsV2.85Ti0.15Sb5 sample, where the “M-shaped” dome is replaced by a simple smooth superconducting dome <ref:2610.12257#pg5>. This difference suggests that while doping can suppress long-range CDW order, the specific low-pressure evolution is governed by different mechanisms and it may be associated with the interplay between SC and elusive short-range CDW fluctuations <ref:2610.12257#pg5>.

Conclusion on Intrinsic Features

The findings provide important insights into the pressure-tuned phase diagram of doped kagome metals, shedding new light on the interplay between charge order and superconductivity in kagome metals <ref:2610.12257#pg4>. The double-dome SC is shown to be an intrinsic and universal feature of the AV3Sb5 family even in the complete absence of long-range CDW <ref:2610.12257#pg5>. The origin of the low-pressure non-monotonic Tc evolution remains unclear, but it may correlate to pressure-induced modifications of the electronic structure near the Fermi level. The paper concludes that these findings provide important insights into the pressure-tuned phase diagram of doped kagome metals, shedding new light on the interplay between charge order and superconductivity in kagome metals <ref:2610.12257#pg5>.

ACKNOWLEDGMENTS This work was supported by the Natural Science Foundation of China (Grant No. 12674162), the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01), Quantum Science and Technology-National Science and Technology Major Project (Grant No. 2024ZD0300104), the National Key Research and Development Program of China (Grant No. 2022YFA1403400), and the Beijing National Laboratory for Condensed Matter Physics (Grant No. 2023BNLCMPKF007) <ref:2610.12257#pg6>.

1. The AI system can accurately predict high-pressure superconducting phase diagrams for doped kagome metals by incorporating pressure-induced dimensional crossover mechanisms, as suggested by the paper: we propose that the second dome is likely also associated with the dimensional crossover induced by pressure.

2. The system can differentiate between superconducting domes arising from competing orders versus those driven by structural changes, specifically recognizing that the formation of two superconducting domes in KV3Sb5 and RbV3Sb5 is believed to account for the formation of two superconducting domes in both materials.

3. The AI can predict the evolution of superconductivity under chemical doping by correlating VHS position with pairing symmetry, as evidenced by: the significant enhancement of superconductivity in CsV2.6Ta0.4Sb5 is attributed to the alignment of VHS with the Fermi level at the M point.

4. The system can model low-pressure non-monotonic behavior by incorporating short-range order effects, hypothesizing that the non-monotonic evolution of Tc observed in the first dome may also correlate to a pressure-induced shift of the VHS relative to the Fermi level.