Proximity-Effect-Induced Anisotropic Superconductivity in a Monolayer Ni-Pb Binary Alloy

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Proximity effect enables superconductivity in normal metals.
• Heterogeneous materials offer routes to novel superconductors and quantum phenomena.

Purpose of the Study:

• Investigate proximity-induced anisotropic superconductivity in a monolayer Ni-Pb binary alloy.
• Fabricate and characterize the Ni-Pb surface alloy on Pb(111).

Main Methods:

• High-temperature growth of Ni-Pb surface alloy on Pb(111).
• Scanning tunneling microscopy/spectroscopy (STM/STS) for high spatial and energy resolution.
• Theoretical calculations to complement experimental findings.

Main Results:

• Observed reduced but anisotropic superconducting gap (Δ_NiPb ≈ 1.0 meV) in the Ni-Pb alloy, distinct from Pb(111) (Δ_Pb ≈ 1.3 meV).
• Higher density of states at the Fermi energy (D(E_F)) in Ni-Pb enhanced coherence peak height.
• Confirmed proximity-induced superconductivity via consistent critical temperature (T_c ≈ 7.1 K) and short decay length (L_d ≈ 3.55 nm).

Conclusions:

• Atomically thick Ni-Pb bimetallic compound demonstrates a pathway to engineer superconducting properties at the 2D limit.
• Proximity effect leads to the emergence of anisotropic superconductivity in the 2D Ni-Pb system.
• Potential for developing new quantum phenomena in engineered 2D superconducting materials.