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Updated: Jul 17, 2025
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Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
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Atomic-Scale Andreev Probe of Unconventional Superconductivity
Wonhee Ko1,2, Sang Yong Song1, Jiaqiang Yan3
1Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Nano Letters
|August 28, 2023
Summary
Tunneling Andreev reflection (TAR) reveals unconventional pairing symmetry in superconductors. This technique probes the sign-changing order parameter and gap structure in materials like FeSe.
Area of Science:
- Condensed matter physics
- Quantum materials science
Background:
- Low-dimensional unconventional superconductors exhibit exotic interface properties.
- Probing pairing symmetry is crucial but challenging for understanding superconductivity.
Purpose of the Study:
- Introduce tunneling Andreev reflection (TAR) as a novel method for probing pairing symmetry.
- Investigate the pairing symmetry and superconducting properties of the FeSe superconductor.
Main Methods:
- Utilize tunneling Andreev reflection (TAR) spectroscopy.
- Analyze Andreev reflections, focusing on quantum interference effects and higher-order processes.
Main Results:
- Directly evidence a sign-changing order parameter in FeSe through suppression and emergence of specific Andreev reflections.
- Reveal two superconducting gaps, suggesting a nodal gap structure.
- Confirm local suppression of superconductivity at nematic twin boundaries, particularly affecting the larger gap.
Conclusions:
- TAR spectroscopy is a powerful tool for atomic-scale insight into quantum materials.
- Unconventional pairing symmetry and inhomogeneous superconductivity in FeSe are characterized.
- The findings advance the understanding of microscopic and interfacial properties in emerging superconductors.
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