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Quantum spin driven Yu-Shiba-Rusinov multiplets and fermion-parity-preserving phase transition in K3C60
Shu-Ze Wang1, Xue-Qing Yu1, Li-Xuan Wei1
1State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
Science Bulletin
|April 9, 2024
Summary
Researchers explored magnetic impurities in superconductors, revealing how their properties influence Yu-Shiba-Rusinov (YSR) states. They discovered a novel quantum phase transition controlled by magnetic anisotropy, crucial for quantum computing advancements.
Area of Science:
- Condensed Matter Physics
- Quantum Computing Materials
Background:
- Magnetic impurities in superconductors are key for studying Yu-Shiba-Rusinov (YSR) states and Majorana zero modes.
- Understanding the link between YSR states and magnetic anisotropy splitting is crucial but poorly understood.
Purpose of the Study:
- To systematically investigate YSR multiplets and Zeeman effects induced by transition-metal impurities (Fe, Cr, Ni) in K3C60.
- To elucidate the relationship between magnetic anisotropy and YSR states in superconductors.
Main Methods:
- Scanning tunneling microscopy (STM) was employed to resolve individual impurities and their induced YSR states.
- Systematic characterization of YSR multiplets and their response to external magnetic fields.
Main Results:
- Identified YSR multiplets and Zeeman effects for Fe, Cr, and Ni impurities in K3C60.
- Observed d orbital-like wave functions for YSR states, mismatched to the K3C60(111) surface symmetry.
- Discovered a fermion-parity-preserving quantum phase transition driven by uniaxial magnetic anisotropy, tunable with magnetic fields.
Conclusions:
- The study clarifies the interplay between magnetic anisotropy and YSR multiplets in superconductors.
- Findings provide insights into controlling YSR states for potential applications in fault-tolerant quantum computation.
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