RESUMEN
The recent discovery of superconductivity in infinite-layer nickelates generates tremendous research endeavors, but the ground state of their parent compounds is still under debate. Here, we report experimental evidence for the dominant role of Kondo scattering in the underdoped Nd1-xSrxNiO2 thin films. A resistivity minimum associated with logarithmic temperature dependence in both longitudinal and Hall resistivities are observed in the underdoped Nd1-xSrxNiO2 samples before the superconducting transition. At lower temperatures down to 0.04 K, the resistivities become saturated, following the prediction of the Kondo model. A linear scaling behavior [Formula: see text] between anomalous Hall conductivity [Formula: see text] and conductivity [Formula: see text]is revealed, verifying the dominant Kondo scattering at low temperature. The effect of weak (anti-)localization is found to be secondary. Our experiments can help in clarifying the basic physics in the underdoped Nd1-xSrxNiO2 infinite-layer thin films.
RESUMEN
Weyl semimetal WTe2 has attracted considerable attention owing to its extremely large, unsaturated and quadratic magnetoresistance. Here, we study the magnetotransport properties of WTe2-δ thin film, which shows an unsaturated and linear magnetoresistance of up to â¼1650%. A more complex and accurate method, known as the maximum entropy mobility spectrum, is used to analyze the mobility and density of carriers. The results show that linear magnetoresistance can be explained by the classical disorder model because the slope of linear magnetoresistance and the crossover field are proportional to the mobility and inverse mobility, respectively. Furthermore, the validity of the maximum entropy mobility spectrum is validated by the Shubnikov-de Haas oscillations. Moreover, at low temperature, we determined that the unsaturated and near-quadratic magnetoresistance in the WTe1.93 thin film can be explained by charge compensation. Note that the electron-hole compensation is broken in the WTe1.42 thin film, which indicates that the carrier scattering induced by the disorder may suppress the charge compensation in the WTe2 sample with defects/dopants. To summarize, the discovery of disorder-induced linear magnetoresistance allows us to explain different magnetoresistance behaviors of WTe2.
RESUMEN
The hydrogenation of monatomic silicene sheet on Ag(111) was studied by scanning tunneling microscopy and density functional theory calculations. It was observed that hydrogenation of silicene at room temperature results in a perfectly ordered γ-(3×3) superstructure. A theoretical model, which involves seven H atoms and rearranged buckling of Si atoms, was proposed and agrees with experiments very well. Moreover, by annealing to a moderate temperature, about 450 K, a dehydrogenation process occurs and the clean silicene surface can be fully recovered. Such uniformly ordered and reversible hydrogenation may be useful for tuning the properties of silicene as well as for controllable hydrogen storage.
RESUMEN
We performed low temperature scanning tunneling microscopy (STM) and spectroscopy (STS) studies on the electronic properties of (â3 × â3)R30° phase of silicene on Ag(111) surface. We found the existence of Dirac Fermion chirality through the observation of -1.5 and -1.0 power law decay of quasiparticle interference (QPI) patterns. Moreover, in contrast to the trigonal warping of Dirac cone in graphene, we found that the Dirac cone of silicene is hexagonally warped, which is further confirmed by density functional calculations and explained by the unique superstructure of silicene. Our results demonstrate that the (â3 × â3)R30° phase is an ideal system to investigate the unique Dirac Fermion properties of silicene.
RESUMEN
The supramolecular pinwheel cluster is a unique chiral structure with evident handedness. Previous studies reveal that the chiral pinwheels are composed of chiral or achiral molecules with polar groups, which result in strong intermolecular interactions such as hydrogen-bonding or dipole interactions. Herein, it is shown that the simple linear aromatic molecule, pentacene, can be self-assembled into large chiral pinwheel clusters on the semimetal Bi(111) surface, due to enhanced intermolecular interactions. The pentacene pinwheels reveal two levels of organizational chirality: the chiral hexamers resulting from asymmetric shifting along the long molecular axis, and chiral arrangement of six hexamers with a rotor motif. Furthermore, a new relation between the local point chirality and organizational chirality is identified from the pinwheels: the former is not essential for the latter in 2D pinwheel clusters of the pentacene molecule.
