Tiny Strain Reveals Separate Superconducting Phases in Kagome Metal
By applying less than 1% strain to CsV3Sb5 crystals, researchers separated two superconducting states that had previously been difficult to distinguish. The strain also raised the temperature at which superconductivity appears while leaving the material's charge-density-wave order largely unchanged. The work may clarify conflicting results about this kagome metal and how its electronic orders interact.
CsV3Sb5 is a kagome metal whose atoms form linked triangles, a geometry tied to competing electronic orders. It hosts a charge density wave near 94 K and becomes superconducting near 2.5 K. Earlier experiments disagreed about whether its superconducting energy gap stays open everywhere or drops to zero at nodal points.
Using a custom piezoelectric apparatus, researchers applied directional stress while probing local electronic behavior with nuclear quadrupole resonance. Tensile strain of +0.90% raised the onset from about 3.0 K to 3.6 K, whereas compression did not. At the strongest stretch, two transitions appeared: one at 3.6 K tied to a nodal state, and another near 3.0 K.
This result may mainly affect physicists and materials researchers by helping reconcile conflicting data and guiding strain-based experiments. Over time, clearer understanding of kagome superconductors could inform designs for quantum devices or low-resistance electronics, though practical applications may remain distant. Funding agencies and technology sectors might take interest if the approach proves broadly useful.