Researchers from Okayama University have demonstrated a method for independently tuning superconductivity in the kagome metal CsV3Sb5 by applying tensile strain. The team reports raising the superconducting transition temperature to 3.6 K with a 0.90% stretch while leaving the material’s charge order unchanged, a surprising result given the typical interplay between these states.
This decoupling offers a new avenue for investigating unconventional superconductivity and resolving conflicting experimental results stemming from the 94 K charge density wave order that precedes the material’s superconducting state. “Our results show that these states can coexist and that uniaxial strain can separate them, giving us a direct way to study each state,” says Professor Shinji Kawasaki.
Tensile Strain Reveals Competing Superconducting States in CsV 3 Sb 5
Applying tensile strain to the kagome metal CsV3Sb5 induces two distinct superconducting transitions, a finding that clarifies conflicting experimental results regarding the material’s superconducting behavior. At a strain of +0.90%, the team observed transitions at both 3.6 K, associated with a nodal superconducting state, and 3.0 K, indicative of a nodeless state. This separation of nearly degenerate states under mechanical stress offers a new method for probing unconventional superconductivity and resolving discrepancies in previous measurements.
This decoupling is unusual; typically, manipulating one electronic order parameter affects others, making this material a valuable platform for fundamental studies. Further analysis revealed a substantial strengthening of the nodal superconducting component under tensile strain. The contribution of this component increased from 10% at zero strain to approximately 26% at +0.90% strain, demonstrating a clear link between mechanical deformation and the material’s electronic structure.
Uniaxial Strain Decouples Superconductivity from Charge Order in Kagome Metals
CsV3Sb5 exhibits a charge density wave order at approximately 94 K, a phenomenon that has complicated efforts to understand its superconducting behavior at lower temperatures. This pre-existing order creates a challenge for researchers attempting to isolate and study the fundamental mechanisms driving superconductivity within the material. At zero strain, the transition began at about 3.0 K, while tensile strain of +0.90% raised it to 3.6 K. This enhancement occurred while the charge density wave remained largely stable, indicating that strain functions as an independent tuning parameter for superconductivity.
This decoupling is significant because hydrostatic pressure typically influences superconductivity by altering charge order, while this method bypasses that connection. The researchers published their findings in Volume 137, Issue 9 of Physical Review Letters on August 28, 2026, and believe this approach could extend beyond CsV3Sb5, offering a general strategy for separating superconductivity from competing orders in other unconventional superconductors like iron-based and heavy-fermion systems.
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