Emergent superconducting fluctuations in compressed kagome superconductor CsV₃Sb₅

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Kagome metals AV3Sb5 exhibit coexisting superconductivity (SC) and charge density wave (CDW) orders.
• Pressure tuning in CsV3Sb5 reveals a two-dome SC phase, destabilizing the CDW, but the SC state's nature remains unclear.

Purpose of the Study:

• Investigate the pressure evolution of the superconducting order parameter in CsV3Sb5.
• Explore the interplay between superconductivity and charge density waves under pressure.

Main Methods:

• Soft point-contact spectroscopy (SPCS) was employed to probe superconducting properties.
• Measurements were conducted on CsV3Sb5 under varying pressure conditions.

Main Results:

• A significant enhancement of the superconducting gap was observed between the two SC domes.
• The superconducting transition broadened, and zero-resistance temperature decreased in this pressure range.
• The temperature dependence of the SC gap deviated from Bardeen-Cooper-Schrieffer (BCS) behavior, indicating strong Cooper pair phase fluctuations.

Conclusions:

• The findings reveal a complex intertwining of CDW and SC orders in compressed CsV3Sb5.
• The results suggest parallels with cuprate superconductors like La2-xBaxCuO4.
• The charge degree of freedom plays a crucial role in the development of these intertwined electronic orders.