馬約拉那準粒子(Majorana quasiparticle)儼然是目前凝態物理學中的聖杯。同時身為自身的反粒子，遵守奇特物理規律的馬約拉那準粒子被認為是未來量子運算發展中最吸引人的候選者。雖然目前已有許多理論提出可能會出現馬約拉那準粒子的系統，例如將磁性材料與s波超導體組合後可能產生的p波超導體，又或是磁性拓樸絕緣體可能承載的軸子(axion)，實驗上我們仍然需要探索更多更廣的可能性及證據，才能循序漸進地揭開此聖杯的真相。本研究利用低溫掃描穿隧顯微鏡及掃描穿隧能譜測量不同形態的FeTe單層成長在拓樸絕緣體Bi2Te3基板上，這些形態包含新發現的六方形態FeTe (hexagonal FeTe)和條紋形態FeTe (stripe FeTe)，以及已知的四方形態FeTe
(tetragonal FeTe)。其中六方形態FeTe和條紋形態FeTe在Bi2Te3上各自出現疊紋圖樣(moiré pattern)，我們藉由模擬FeTe與Bi2Te3的原子解析形貌，成功得出疊紋圖樣可能的原子模型。除了不同形態FeTe的分析，我們也發現六方形態FeTe和條紋形態FeTe會因後退火的過程逐漸轉變為四方形態FeTe，說明此兩種形態可能為四方形態FeTe的前指標(precursor)。受四方形態FeTe在Bi2Te3上已知具有超導性和雙共線(bi-collinear)反鐵磁性的特性而啟發，我們希望新發現的六方形態FeTe和條紋FeTe能提供磁性拓樸絕緣體及拓樸超導體更多的可能性，在追尋馬約拉那準粒子的路上付出微小的貢獻。

The Majorana quasiparticle is currently the Holy Grail of condensed matter physics. As its own antiparticle, the Majorana quasiparticle, which follows unusual physical laws, is considered to be the most attractive candidate for the development of quantum computing in the future. Although many theories have proposed systems in which Majorana quasiparticle may appear, such as the p-wave superconductor produced by combining magnetic materials with s-wave superconductors, or the magnetic topological insulator that may carry anyon, we still need to explore more and wider possibilities and evidences in experiments, in order to gradually reveal the truth of the Holy Grail. In this study, low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy were used to measure different phases of FeTe monolayers grown on the topological insulator Bi2Te3 substrate. These phases include the newly discovered hexagonal FeTe and stripe FeTe, and already-known tetragonal FeTe. Among them, hexagonal FeTe has a moiré pattern with a hexagonal lattice on Bi2Te3, and the stripe FeTe also has a more complicated orthorhombic lattice as moiré pattern. Based on their atomic-resolution topographies, we have also successfully simulated the possible atomic models of the moiré patterns that appear on hexagonal FeTe and stripe FeTe. In addition to the analysis of different phases of FeTe, we also found that hexagonal FeTe and stripe FeTe will gradually transform into tetragonal FeTe due to the post-annealing process, indicating that these two phases may be the precursors of tetragonal FeTe. Inspired by the superconductivity and bi-collinear antiferromagnetism of tetragonal FeTe on Bi2Te3, we hope that the newly discovered hexagonal FeTe and stripe FeTe grown on Bi2Te3 provides more possibilities for magnetic topological insulators and topological superconductors, and make a tiny contribution to the pursuit of the Majorana quasiparticle.

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