Guo Xiao, Zhu Qiuhao, Zhou Liyan, Yu Wei, Lu Wengang, Liang Wenjie
Songshan Lake Materials Laboratory, Dongguan, Guangdong, China.
Beijing National center for Condensed Matter Physics, Beijing Key Laboratory for Nanomaterials and Nanodevices, Institute of Physics, Chinese Academy of Sciences, Beijing, P.R. China.
Nat Commun. 2021 Mar 10;12(1):1566. doi: 10.1038/s41467-021-21492-x.
The Kondo effect offers an important paradigm to understand strongly correlated many-body physics. Although under intensive study, some of the important properties of the Kondo effect, in systems where both itinerant coupling and localized coupling play significant roles, are still elusive. Here we report the evolution and universality of the two-stage Kondo effect, the simplest form where both couplings are important using single molecule transistor devices incorporating Manganese phthalocyanine molecules. The Kondo temperature T* of the two-stage Kondo effect evolves linearly against effective interaction of involved two spins. Observed Kondo resonance shows universal quadratic dependence with all adjustable parameters: temperature, magnetic field and biased voltages. The difference in nonequilibrium conductance of two-stage Kondo effect to spin 1/2 Kondo effect is also identified. Messages learned in this study fill in directive experimental evidence of the evolution of two-stage Kondo resonance near a quantum phase transition point, and help in understanding sophisticated molecular electron spectroscopy in a strong correlation regime.
近藤效应为理解强关联多体物理提供了一个重要范例。尽管已进行了深入研究，但在巡游耦合和局域耦合都起重要作用的系统中，近藤效应的一些重要性质仍不明确。在此，我们利用包含锰酞菁分子的单分子晶体管器件，报道了两阶段近藤效应的演化和普适性，这是两种耦合都很重要的最简单形式。两阶段近藤效应的近藤温度T*随所涉及的两个自旋的有效相互作用呈线性演化。观察到的近藤共振对所有可调参数（温度、磁场和偏置电压）呈现出普遍的二次依赖性。还确定了两阶段近藤效应与自旋1/2近藤效应在非平衡电导方面的差异。本研究中获得的信息填补了量子相变点附近两阶段近藤共振演化的直接实验证据，并有助于理解强关联体系中复杂分子电子能谱。
