Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Phys Rev Lett. 2019 Oct 25;123(17):176601. doi: 10.1103/PhysRevLett.123.176601.
Motivated by recent STM experiments, we explore the magnetic field induced Kondo effect that takes place at symmetry protected level crossings in finite Co adatom chains. We argue that the effective two-level system realized at a level crossing acts as an extended impurity coupled to the conduction electrons of the substrate by a distribution of Kondo couplings at the sites of the chain. Using auxiliary-field quantum Monte Carlo simulations, which quantitatively reproduce the field dependence of the zero-bias signal, we show that a proper Kondo resonance is present at the sites where the effective Kondo coupling dominates. Our modeling and numerical simulations provide a theoretical basis for the interpretation of the STM spectrum in terms of level crossings of the Co adatom chains.
受最近的 STM 实验的启发，我们研究了在有限 Co 吸附原子链中的对称保护能级交叉处发生的磁场诱导的近藤效应。我们认为，在能级交叉处实现的有效两能级系统充当扩展的杂质，通过链上各点的近藤耦合分布与衬底的传导电子耦合。使用辅助场量子蒙特卡罗模拟，该模拟定量地再现了零偏信号的场依赖性，我们表明，在有效近藤耦合占主导地位的位置存在合适的近藤共振。我们的建模和数值模拟为用 Co 吸附原子链的能级交叉来解释 STM 谱提供了理论基础。
