Charge-density wave mediated quasi-one-dimensional Kondo lattice in stripe-phase monolayer 1T-NbSe2.

The heavy fermion physics is dictated by subtle competing exchange interactions, posing a challenge to their understanding. One-dimensional (1D) Kondo lattice model has attracted special attention in theory, because of its exact solvability and expected unusual quantum criticality. However, such experimental material systems are extremely rare. Here, we demonstrate the realization of quasi-1D Kondo lattice behavior in a monolayer van der Waals crystal NbSe2, that is driven into a stripe phase via Se-deficient line defects. Spectroscopic imaging scanning tunneling microscopy measurements and first-principles calculations indicate that the stripe-phase NbSe2 undergoes a novel charge-density wave transition, creating a matrix of local magnetic moments. The Kondo lattice behavior is manifested as a Fano resonance at the Fermi energy that prevails the entire film with a high Kondo temperature. Importantly, coherent Kondo screening occurs only in the direction of the stripes. Upon approaching defects, the Fano resonance exhibits prominent spatial 1D oscillations along the stripe direction, reminiscent of Kondo holes in a quasi-1D Kondo lattice. Our findings provide a platform for exploring anisotropic Kondo lattice behavior in the monolayer limit.

[Aggregation number determination of gemini anionic surfactant micelle by intrinsic fluorescence quenching].

The p-phendioxyl base in the spacer of gemini surfactant C11pPHCNa emits fluorescence under exciting. When the gemini concentration is over 0.45 mmol x L(-1), the topological structure of the excitation spectra yields various changes resulting in them being significantly different from the corresponding absorption spectra. As the aromatic base in the spacer of C11pPHCNa obviously quenches the fluorescence of pyrene that is as additional probe, it is hardly to determine the average micelle aggregation number by the usual method of quenching pyrene. In the present paper, using the property of methylviologen (MV2+) effectively quenching the fluorescence of C11pPHCNa, the authors established the method to determine the average aggregation number N of C11pPHCNa micelle. For individual C11pPHCNa micelle, N was determined to be 20.6 at c=2 mmol L(-1), while the average aggregation number of C11pPHCNa/C12-2-E1-C12 x 2Br mixed micelle in the aqueous solution with a total concentration of 2 mmol x L(-1) and C11pPHCNa of mole fraction 0.3 in the bulk was obtained to be 11.8.