[论文解读] Majorana Signatures in Planar Tunneling through a Kitaev Spin Liquid

Weiyao Li, Vitor Dantas+2 more|arXiv (Cornell University)|Feb 16, 2026

Advanced Condensed Matter Physics被引用 0

一句话总结

该论文提出一种穿过空位掺杂的Kitaev自旋液体的平面隧穿方案，通过非弹性隧穿光谱检测空位绑定的Majorana模态，并将谱与实空间自旋相关性联系起来。

ABSTRACT

We propose a planar tunneling setup to probe vacancy-bound Majorana modes in the chiral Kitaev spin liquid. In this geometry, the inelastic tunneling conductance can be expressed directly in terms of real-space spin correlations, establishing a link between measurable spectra and the underlying fractionalized excitations. We show that spin vacancies host localized Majorana states that generate sharp near-zero-bias features, well separated from the continuum of bulk spin excitations. Compared to local STM measurements, the planar configuration naturally enhances the signal by coherently summing over multiple vacancies, reducing spatial resolution requirements. Our results demonstrate a realistic and scalable route to detect Majorana excitations in Kitaev materials.

研究动机与目标

• Motivate the detection of fractionalized Majorana excitations in Kitaev spin liquids.
• Extend planar tunneling probes to vacancy-doped Kitaev layers to enhance Majorana signal visibility.
• Derive an expression for inelastic tunneling conductance in terms of real-space spin correlations.
• Compute vacancy-modified spin dynamics to identify near-zero-energy Majorana signatures.

提出的方法

• Derive an effective low-energy tunneling Hamiltonian via Schrieffer–Wolff transformation yielding exchange and potential-scattering terms.
• Express inelastic current dI/dV in terms of the retarded spin correlator C^R and lead bubble Pi^R.
• Show d^2I/dV^2 is proportional to a sum of dynamical spin structure factors S^{αα}(r,r';ω).
• Decompose the disorder-averaged spin spectral function into bulk, near-vacancy, and dangling (intra-/inter-vacancy) contributions.
• Compute spin correlations by diagonalizing the quadratic Majorana Hamiltonian in vacancy backgrounds and using Bogoliubov transformations.

实验结果

研究问题

• RQ1 Can planar inelastic tunneling detect vacancy-bound Majorana modes in a Kitaev spin liquid?
• RQ2 How do vacancy-induced bound states and flux configurations modify the dynamical spin correlations relevant to tunneling?
• RQ3 What is the relative contribution of bulk versus vacancy-related spin dynamics to the measured IETS signal?
• RQ4 Does the planar geometry amplify vacancy Majorana signatures compared to local STM measurements?

主要发现

• d^2I_inel/dV^2 maps directly to a sum of dynamical spin correlations S^{αα}(r,r';ω) with ω = eV, linking spectra to fractionalized excitations.
• Vacancies bind Z2 fluxes, creating low-energy dangling Majorana modes that generate near-zero-bias spectral features within the bulk gap.
• Near-zero-bias weight scales with vacancy density, evidencing coherent contributions from vacancy-induced Majorana modes.
• Dangling (intra-vacancy) contributions dominate the subgap near-zero-bias signal, while inter-vacancy dangling terms show subleading, oscillatory behavior depending on vacancy geometry.
• Planar tunneling enhances the Majorana signal by coherently summing over many vacancies, reducing the need for extreme spatial resolution.
• Numerical results at κ=0.02J, h=0.05J and vacancy densities up to 4% show a main bulk two-flux peak around Δ_{2f} ≈ 0.26J with in-gap vacancy-related features.