The unique tri-layered atomic structure of MoS2 monolayer favors formation of sulfur vacancy lines (SVL), which has been confirmed by both theoretical and experimental studies. This defect could be used as a template to accommodate atomic metal chains, which is an interesting research topic in recent years. In this study, we investigated the magnetic properties of atomic 3d transition metal (V, Cr, Mn and Fe) chains adsorbed along a SVL of monolayer MoS2 using first-principles calculations. All atomic transition-metal (TM) chains could adsorb stably with large binding energies. The magnetic orders and exchange interactions of 3d transition-metal chains were dramatically influenced by the MoS2 substrate. The magnetic ground state of the V and Cr chains remained unchanged after anchoring onto MoS2; however the magnetic interactions weakened compared to those of their free-standing cases. Mn and Fe chains showed transitions from ferromagnetic (FM) coupling in a freestanding chain to antiferromagnetic (AFM) coupling on the SVL of MoS2. The magnetic coupling in atomic transition metal chains is mediated by Mo atoms in the vicinity of atomic chains, which is governed by the combination of through-bond and through-space interactions. It was found that through-bond coupling is dominant in FM V/MoS2, and through-space coupling is dominant in the AFM state of Cr/MoS2, Mn/MoS2 and Fe/MoS2. The electronic properties, magnetic order and exchange interactions of atomic 3d transition-metal chain on SVL of MoS2 can be tuned by the uniaxial strain applied along the chain direction.

It is highly desirable to fabricate two-dimensional ferromagnetic membranes based on orthodox magnetic elements because of their inherent magnetic properties. In this work, we report on two superstructures including a honeycomb-like lattice and identical nanocluster arrays formed by depositing Fe on Sb(111). Combined with first-principles calculations, both detailed atomic structures have been clarified. The honeycomb structure consists of a single layered Fe–Sb phase, and the cluster phase is assigned as a (3 × 3) Fe3Sb7 superlattice. Both structural phases exhibit high magnetic moments localized on d bands of Fe. Our results provide a method to fabricate 2D magnetic superstructures possessing great potential in the realization of the Haldane model, spintronics applications, and single atom catalysis.Keywords: honeycomb lattice; identical cluster; Sb(111); scanning tunneling microscopy;

We report on a Kondo effect on Co/Sb(111) mediating topological protection of the surface states against local magnetic perturbations. A sharp scanning tunneling spectroscopic peak near the Fermi energy is interpreted as a fingerprint of the Kondo resonance with a high Kondo temperature of about 200 K. Density function theory calculations reveal that the protruding Co adatoms are responsible for the Kondo peak, while the Co atoms underneath present as nonmagnetic impurities. By identifying the quasiparticle interference wavevectors, we demonstrate that only scattering channels related to backscattering confinements are observed for surfaces with and without the Co adsorption. It suggests that the Kondo effect suppresses the backscattering of the topological surface states and may help to expand the functionality of magnetically coupled topological materials for spintronics applications.Keywords: Kondo effect; quasiparticle interference; Sb(111); time reversal symmetry; topological surface states;

Growth and surface electronic states of Co nanoislands supported by Cu–9 at.%Al(111) are investigated by low temperature scanning tunneling microscopy. Deposition of about 0.25 monolayer of Co atoms causes the formation of flat Co nanoislands with thicknesses ranging from monolayer to triple layer. Scanning tunneling spectroscopy measurements reveal that a Tamm-type surface state exists on the Co islands and its energy varies with the thicknesses and stacking manners. In addition, density functional theory calculations conclude that the surface states of the mono- and bilayer nanoislands mainly originate from the hybridization between Co d bands and sp   bands of the substrate and the Co d3z2−r2d3z2−r2 minority-spin bands, respectively.Highlights► Co islands with different thicknesses were grown on Cu–9at%Al(111). ► Surface electronic states of Co islands were investigated by STM. ► Energies of surface states vary with the thicknesses and stacking manners. ► The origins of surface states were clarified by DFT calculations.

To observe molecular orbitals using scanning tunneling microscopy, well-ordered oxidized layers on Cu(001) were fabricated to screen the individual adsorbed cobalt phthalocyanine (CoPc) molecules from the electronic influence of the metal surface. Scanning tunneling microscope images of the molecule on this oxidized layer show similarities to the orbital distribution of the free molecule. The good match between the differential conductance mapping images and the calculated charge distribution at energy levels corresponding to the frontier orbitals of CoPc provides more evidence of the screening of the oxidized layer from interactions between the metal surface and supported molecules.Highlights► STM is a powerful tool to depict molecular orbitals, a basic concept of chemistry. ► Native copper oxide layer was fabricated for adsorption of cobalt phthalocyanine. ► Detailed orbitals of CoPc were successfully observed for the 1st time by STM. ► The effect of the layer is explained by DFT quantum mechanical computations.

Bias-dependent features of the insulating NaCl layer grown on Cu(001) have been investigated by scanning tunneling microscopy/spectroscopy (STM/STS). The apparent layer thickness of the NaCl film is variable at bias voltages ranging from 2.8 to 3.2 V as well as from 4.0 to 5.0 V, and the Moiré pattern induced by NaCl–Cu lattice mismatch also shows bias dependence. The z–V (dz/dV–V) curves and dI/dV mapping measurements reveal that the resonant tunneling between the image potential states (IPSs) on Cu(001) and the Fermi level of the STM tip leads to drastic variations of these features.

The morphologies, self-assembly structures, and stability of cobalt−phthalocyanines (CoPc) molecules adsorbed on Cu(001) with coverage ranging from 0.2 monolayer (ML) to 1.6 ML are investigated by ultrahigh-vacuum low-temperature scanning tunneling microscopy (UHV LT-STM) at liquid nitrogen temperature. Upon increasing the deposition of CoPc molecules various structures, such as isolated adsorption, quasi-hexagonal structure, √29 × √29 structure, are well characterized by the corresponding high-resolution STM images. The CoPc−CoPc intermolecular interaction and CoPc−substrate interfacial interaction dominate the structural evolutions. For the coverage higher than 1 ML, CoPc molecules preferentially locate on top of the molecules underneath and organize into √58 × √58 structure. As more and more CoPc molecules adsorb on the first layer, in some √58 × √58 regions molecular insertion leads to the formation of the √29 × √29 domain to effectively decrease the energy of the whole system.

We demonstrate the use of bolometric force backaction in lever-based miniature Fabry–Pérot (FP) optical cavity for micro-cantilever control. In our experiment, low finesse FP microcavity is formed by polished fiber end and mass loaded micro-cantilever. We show that the dynamics of micro-cantilever can be deeply modified when photon intensity stored in the FP microcavity is sufficiently large. For blue microcavity detuning, we confirm this control mechanism can optimize the dynamics of micro-cantilever and dramatically reduce its Brownian motion amplitude without deteriorating force resolution. This effective and low-cost control method can be simply realized in most optical detection force microscopes.

Pd/Ag bimetallic nanoparticles have been synthesized successfully by reducing PdCl2 and AgNO3 mixture in ethylene glycol solution using the solvothermal method. The prepared samples have been characterized by UV–vis, XRD, TEM, HRTEM, EDS, and XPS, respectively. Moreover, the bimetallic particles possess alloy and core-shell structure from the HRTEM images. Here, the lattice fringe spacing of Pd/Ag bimetallic nanoparticles corresponds to its (111) plane, which is between that of the Pd and Ag nanoparticles prepared under the same conditions. Furthermore, the possible formation mechanism and factors influencing the formation of Pd/Ag bimetallic nanoparticles, such as reaction temperature and time, have also been investigated.

The unique tri-layered atomic structure of MoS2 monolayer favors formation of sulfur vacancy lines (SVL), which has been confirmed by both theoretical and experimental studies. This defect could be used as a template to accommodate atomic metal chains, which is an interesting research topic in recent years. In this study, we investigated the magnetic properties of atomic 3d transition metal (V, Cr, Mn and Fe) chains adsorbed along a SVL of monolayer MoS2 using first-principles calculations. All atomic transition-metal (TM) chains could adsorb stably with large binding energies. The magnetic orders and exchange interactions of 3d transition-metal chains were dramatically influenced by the MoS2 substrate. The magnetic ground state of the V and Cr chains remained unchanged after anchoring onto MoS2; however the magnetic interactions weakened compared to those of their free-standing cases. Mn and Fe chains showed transitions from ferromagnetic (FM) coupling in a freestanding chain to antiferromagnetic (AFM) coupling on the SVL of MoS2. The magnetic coupling in atomic transition metal chains is mediated by Mo atoms in the vicinity of atomic chains, which is governed by the combination of through-bond and through-space interactions. It was found that through-bond coupling is dominant in FM V/MoS2, and through-space coupling is dominant in the AFM state of Cr/MoS2, Mn/MoS2 and Fe/MoS2. The electronic properties, magnetic order and exchange interactions of atomic 3d transition-metal chain on SVL of MoS2 can be tuned by the uniaxial strain applied along the chain direction.