When cooled below a specific threshold temperature, superconductors lose their electrical resistance. Their physical mechanisms and potential for application appeal to many scientists in the field.
The pressurized kagome superconductor CsV3Sb5 exhibits an emerging charge order that competes with superconductivity, according to a study published in Nature by a research team led by Professor Xianhui Chen from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences.
It is complicated how different ordering tendencies of superconducting materials interact with one another. Intertwined orders have recently been put forth from a fresh viewpoint that emphasizes the cooperation of various orders.
The finding of multiple electronic orders in the kagome superconductors AV3Sb5 (where A stands for K, Rb, or Cs) offers a promising starting point for investigating the physics of intertwined orders.
The word “kagome” in Japanese describes a bamboo basket weaving pattern. Flat bands, Dirac points, and van Hove singularities are a few of the band structures in this two-dimensional (2D) lattice pattern.
An earlier theory in a 2D kagome lattice predicted unusual superconductivity and a wide range of electronic orders close to the van Hove singularities.
In earlier research, Professor Chen’s team revealed the triple-Q charge density wave (CDW) and a brand-new electronic nematicity. In pressure experiments, they also discovered an unusual competition between superconductivity and CDW state.
The researchers examined the development of CDW and superconductivity in CsV3Sb5 under pressure based on their earlier research. Between the pressures of Pc1≅0.58 GPa and Pc2≅2.0 GPa, where superconductivity was severely suppressed, an emergent CDW state was seen.
The emerging CDW was suppressed, and superconductivity took over when the pressure reached Pc2. These results imply that CDW and superconductivity are in fierce competition.
The researchers also discovered pressure-independent charge fluctuations above the CDW transition temperature through the nuclear spin-lattice relaxation measurement, which is evidence for the existence of electronic correlation effects in the 2D kagome lattice.
A Hebel-Slichter coherent peak was visible in conventional superconductors below the superconducting transition temperature. However, CsV3Sb5 did not exhibit this peak, indicating a potential for unusual superconductivity in this pressurized kagome superconductor.
The study paves the way for learning more about the kagome superconductors’ unusual superconductivity by revealing their evolution and new electronic correlation effects.
Zheng, L., et al. (2022) Emergent charge order in pressurized kagome superconductor CsV3Sb5. Nature. doi:10.1038/s41586-022-05351-3.