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Published on: August 2, 2019
Phase-sensitive evidence for pair density waves in a kagome superconductor
Xiao-Yu Yan1, Guowei Liu1,2, Hanbin Deng1
1State Key Laboratory of Quantum Functional Materials, Department of Physics, and Guangdong Basic Research Center of Excellence for Quantum Science, Southern University of Science and Technology, Shenzhen 518055, China.
Summary
Researchers observed a nonmagnetic pair-breaking effect in a kagome superconductor. Dilute nonmagnetic impurities suppressed pair density wave modulations, confirming its sensitivity to scattering.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Materials
Background:
- Pair density wave (PDW) is a superconducting state with periodic modulations.
- PDW is theoretically sensitive to nonmagnetic scattering, but experimental evidence is scarce.
- Kagome superconductors offer a unique platform to study exotic electronic states.
Purpose of the Study:
- To experimentally investigate the nonmagnetic pair-breaking effect on a pair density wave in a kagome superconductor.
- To probe the sensitivity of PDW to nonmagnetic impurities.
- To understand the interplay between PDW, charge order, and superconductivity in kagome systems.
Main Methods:
- Utilized designer atomic nonmagnetic impurities to dope a kagome superconductor.
- Employed high-precision scanning tunneling microscopy (STM) at 30 mK.
- Performed Josephson STM with a superconducting tip and normal STM to detect PDW modulations.
Main Results:
- Observed 2 × 2 pair density modulations and 2 × 2 pairing gap modulations.
- Found substantial suppression of these modulations upon doping with dilute isovalent nonmagnetic impurities.
- Demonstrated that charge order and uniform superconductivity remained robust against impurity doping.
- Correlated atomic dopant locations with local PDW suppression, indicating a nonmagnetic pair-breaking effect.
Conclusions:
- The study provides the first experimental evidence of a nonmagnetic pair-breaking effect on a pair density wave.
- The findings support the kagome superconductor's ground state as a correlated topological phase with superconducting loop currents.
- This work opens new avenues for exploring and manipulating exotic superconducting states in quantum materials.
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