AI 中文总结
研究通过扫描隧道显微镜和理论计算发现Bi₂Te₃上Fe吸附原子的对称性因姜-泰勒畸变从C₃v降至C₁v，解释了实验观测的微分电导图对称性破缺现象。
AI 中文摘要
我们报道了Bi₂Te₃(111)表面上Fe吸附原子的联合扫描隧道显微镜与原子级理论研究。4.5K下的形貌成像显示，fcc和hcp hollow位点的Fe吸附原子呈现三重对称衬度，与吸附位点的C₃v对称性一致。然而，同步获取的微分电导（dI/dV）图显示对称性显著降低，最近邻Te位点处观察到的微分衬度可作为证据。密度泛函理论计算表明，Fe/Bi₂Te₃系统发生静态姜-泰勒畸变，使吸附对称性从C₃v降低至C₁v，且畸变构型的能量比未畸变构型低72.5meV。轨道投影态密度计算显示，费米能级附近的占据态主要由dₓz和dᵧz轨道贡献，而未占据态主要为d_z²、dₓ²₋ᵧ²和dₓᵧ轨道特征。这些轨道的局域态密度与实验dI/dV谱定性吻合良好。此外，采用紧束缚格林函数方法模拟的局域态密度图与实验dI/dV图吻合良好，证实对称性降低源于C₁v结构畸变。
英文摘要
We report a combined scanning tunneling microscopy and atomistic theoretical study of Fe adatoms on the Bi$_2$Te$_3$(111) surface. Topographic imaging at $4.5$~K shows that Fe adatoms in fcc and hcp hollow sites exhibit a threefold-symmetric contrast, consistent with the $C_{3v}$ symmetry of the adsorption site. However, simultaneously acquired differential conductance ($dI/dV$) maps reveal a pronounced reduction in symmetry, evidenced by differential contrast observed at nearest-neighbor Te sites. Density functional theory calculations show that the Fe/Bi$_2$Te$_3$ system undergoes a static Jahn--Teller distortion, reducing the adsorption symmetry from $C_{3v}$ to $C_{1v}$, with the distorted configuration favored by $72.5$~meV. Orbital-projected density of states calculations show that the occupied states near the Fermi level are dominated by $d_{xz}$ and $d_{yz}$ orbitals, whereas the unoccupied states are primarily of $d_{z^2}$, $d_{x^2-y^2}$, and $d_{xy}$ character. The local density of states from these orbitals is in good qualitative agreement with experimental $dI/dV$ spectra. Furthermore, simulated local-density-of-states maps using a tight-binding Green's function approach are consistent with experimental $dI/dV$ maps, confirming that the reduced symmetry originates from the $C_{1v}$ structural distortion.
Comments7 pages, 5 figures
