发表机构
Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL); Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University; Department of Chemistry, Graduate School of Science, Tohoku University; Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University; Center for Spintronics Research Network, Tohoku University; Institute of Physics (FZU), Czech（洛桑联邦理工学院物理研究所; 西安交通大学材料科学与工程学院自旋电子学与量子系统中心（材料力学行为国家重点实验室）; 东北大学理学研究府化学系; 东北大学先进材料跨学科研究所; 东北大学自旋电子学研究网络中心; 捷克物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究石墨烯/Ir(111)上Sm吸附原子的电荷态、磁激发与近藤效应，明确其可变电荷态的起源，首次观测到镧系吸附原子的近藤共振。
AI 中文摘要
利用低温扫描隧道显微镜（STM），我们研究了石墨烯/Ir(111)上单个Sm吸附原子的电荷态、磁激发和近藤特征。根据相邻原子的数量和距离，Sm原子可处于两种离散的电荷态；在特定距离下，STM针尖的电场会诱导这两种电荷态之间发生可逆转变，导致图像中出现同心电荷环。仅处于其中一种电荷态的原子会在dI/dV谱中表现出磁激发，两种磁激发分别位于35 meV和54 meV处，对应从J=1/2基态双重态到首个晶体场分裂的J=3/2多重态的跃迁。结合更高能量下的原子内交换激发，这些观测表明Sm原子向衬底转移了1个6s电子，同时保留了气相的4f电子填充。对于镧系吸附原子，我们首次观测到近藤共振；近藤峰的塞曼分裂显示Sm保留了其气相的大g因子。将dI/dV谱与共隧穿理论对比，可得到作用于4f壳层进而作用于J=3/2四重态的晶体场，证实Sm⁺为基态，Sm²⁺能量接近，从而解释了我们观测到的可变电荷态。
英文摘要
Using low-temperature scanning tunneling microscopy we investigate the charge state, magnetic excitations, and Kondo features of individual Sm adatoms on graphene/Ir(111). Depending on the number and distance of their neighbors, Sm atoms can be in two discrete charge states. At certain distances, a reversible transition between these two states is induced by the electric field of the STM tip leading to concentric charge rings in the images. Only atoms in one of the two charge states exhibit magnetic excitations in d$I$/d$V$ spectra. Two such excitations are located at 35~meV and 54~meV and related to transitions from the $J = 1/2$ ground state doublet to the first crystal field split $J = 3/2$ multiplet. Together with the intra-atomic exchange excitations at higher energy, these observations indicate that Sm transfers one $6s$ electron to the substrate while it retains its gas-phase $4f$ filling. New for lanthanide adatoms, we observe a Kondo resonance. The Zeeman splitting of the Kondo peak reveals that Sm retains its large gas-phase $g$-factor. Comparison of d$I$/d$V$ spectra to cotunneling theory yields the crystal field acting on the $4f$ shell and, consequently, on the $J = 3/2$ quadruplet, confirms Sm$^+$ as the ground state, and identifies Sm$^{2+}$ as being energetically close, thereby rationalizing our observation of variable charge states.
