Doping of semiconductors by impurity atoms enabled their widespread technological application in microelectronics and optoelectronics. However, doping has proven elusive for strongly confined colloidal semiconductor nanocrystals because the synthetic challenge how to introduce single impurities, as well a lack fundamental understanding this heavily doped limit under strong quantum confinement. We developed method dope with metal enabling control band gap Fermi energy. A combination optical...

The superconducting ${\mathrm{R}}_{1.4}$ ${\mathrm{Ce}}_{0.6}$ ${\mathrm{RuSr}}_{2}$ ${\mathrm{Cu}}_{2}$ ${\mathrm{O}}_{10\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ materials are also magnetically ordered at ${\mathrm{T}}_{\mathrm{N}}$\ensuremath{\gg}:${\mathrm{T}}_{\mathrm{c}}$ (${\mathrm{T}}_{\mathrm{c}}$\ensuremath{\sim}42, 32 and ${\mathrm{T}}_{\mathrm{N}}$\ensuremath{\sim}180, 122 K for R=Gd Eu, respectively). Magnetic susceptibility M\"ossbauer spectroscopy show that...

The interplay between magnetism and superconductivity can lead to unconventional proximity Josephson effects. A related phenomenon that has recently attracted considerable attention is the superconducting diode effect, in which a nonreciprocal critical current emerges. Although diodes based on superconductor/ferromagnet (S/F) bilayers were demonstrated more than decade ago, precise underlying mechanism remains unclear. While not formally linked this Fulde-Ferrell-Larkin-Ovchinikov (FFLO)...

Classical percolation theory is concerned with the onset of geometrical connectivity and accompanied electrical in disordered systems. It was found, however, that many systems, such as various composites, onsets are not simultaneous correlation between them depends on physical processes tunneling. The difference above two types systems consequences for transport properties latter composites have been largely ignored past. application scanning local probe microscopies some recent theoretical...

In many composites, the electrical transport takes place only by tunneling between isolated particles. For a long time, it was quite puzzle how, in spite of incompatibility and percolation networks, these composites conform well to theory. We found, conductance atomic force microscopy measurements on granular metals, that is apparent cut off non-nearest-neighbors brings about this behavior. particular, cluster shown consist nearest-neighbors subnetwork full network.

Photoluminescence excitation spectroscopy and scanning-tunneling are used to study the electronic states in CdSe quantum rods that manifest a transition from zero-dimensional one-dimensional quantum-confined structure. Both optical tunneling spectra show level structure depends primarily on diameter of rod not its length. With increasing diameter, band gap excited state spacings shift red. The was assigned using multiband effective-mass model, showing similar dependence dimensions.

The ability to tailor the properties of semiconductor nanocrystals through creating core/shell heterostructures is cornerstone for their diverse application in nanotechnology. band-offsets between heterostructure components are determining parameters optoelectronic properties, dictating example degree charge-carrier separation and localization. So far, however, no method was reported direct measurement these factors colloidal only indirect information could be derived from optical...

We demonstrate tuning of the electronic level positions with respect to vacuum in colloidal InAs nanocrystals using surface ligand exchange. Electrochemical as well scanning tunneling spectroscopy measurements reveal that is largely dependent on nanocrystal size and linking group, while polarity molecules has a lesser effect. The implications affecting system through its capping are illustrated prototype devices.

We have applied scanning tunneling spectroscopy in studies of the electronic level structure surface-functionalized colloidal Si nanocrystals (Si-NCs) as a function their size for various capping ligands. The energy gaps extracted from spectra increase with decreasing NC size, manifesting effect quantum confinement. This is consistent blueshift revealed by photoluminescence (PL) dodecene functionalized Si-NCs. measured on NCs NH4Br or allylamine show band-edge shifts toward higher energies,...

Abstract Electron pairing in the vast majority of superconductors follows Bardeen–Cooper–Schrieffer theory superconductivity, which describes condensation electrons into pairs with antiparallel spins a singlet state an s -wave symmetry. Unconventional superconductivity was predicted single-layer graphene (SLG), p or chiral d symmetry, depending on position Fermi energy respect to Dirac point. By placing SLG electron-doped (non-chiral) superconductor and performing local scanning tunnelling...

The discrete molecular-level spectrum of an isolated ${\mathrm{C}}_{60}$ molecule is resolved and its interplay with single-electron charging effects studied using room-temperature cryogenic scanning tunneling spectroscopy. current-voltage spectra these molecules exhibit rich structures resulting from both resonant through the levels effects. In particular, we observe degeneracy lifting within molecular orbitals, probably due to Jahn-Teller effect local electric fields. Theoretical fits...

The use of a combination tunneling and optical spectroscopy to investigate the size shape-dependent level structure single-electron charging phenomena in semiconductor nanocrystals is reviewed. artificial atom character nanocrystal quantum dots manifested both discrete multiplicity data, revealing s p atomic-like states. Such states can be directly imaged using scanning microscopy, providing extent symmetry envelope wavefunctions. A detailed description effect geometry on spectra presented....

Current imaging scanning tunneling microscopy is used to observe the electronic wave functions in InAs/ZnSe core/shell nanocrystals. Images taken at a bias corresponding s conduction band state show that it localized central core region, while images higher probing p reveal extends shell. This supported by optical and spectroscopy data demonstrating s-p gap closes upon shell growth. Shapes of current resemble atomlike envelope quantum dot calculated within particle box model.

Scanning tunneling spectroscopy measurements conducted on epitaxially grown bilayers of half-metallic ferromagnetic La${}_{2/3}$Ca${}_{1/3}$MnO${}_{3}$ (LCMO) superconducting (100)YBa${}_{2}$Cu${}_{3}$O${}_{7\ensuremath{-}\ensuremath{\delta}}$ reveal long-range penetration order into the LCMO. This anomalous proximity effect manifests itself in spectra measured LCMO layer as gaps and zero-bias conductance peaks. Remarkably, these proximity-induced spectral features were observed for with...

Obtaining insight into, and ultimately control over, electronic doping of halide perovskites may improve tuning their remarkable optoelectronic properties, reflected in what appear to be low defect densities as expressed various charge transport optical parameters. Doping is important for because it determines the electrical field within semiconducting photoabsorber, which strongly affects collection efficiency photogenerated charges. Here we report on intrinsic methylammonium lead...

Photovoltaic solar cells operate under steady-state conditions that are established during the charge carrier excitation and recombination. However, to date no model of recombination scenario in halide perovskites has been proposed. In this Letter we present such a is based on single type center, which deduced from our measurements illumination intensity dependence photoconductivity ambipolar diffusion length those materials. The relation between results time-resolved measurements, as...

The electronic properties of metal-semiconductor nanojunctions are investigated by scanning tunneling spectroscopy gold-tipped CdSe rods. A gap similar to that in bare nanorods is observed near the nanodumbbell center, while subgap structure emerges nanocontact. This behavior attributed formation interface states vanish rapidly towards center rod, consistent with theoretical predictions. These lead also modified Coulomb staircase, and some cases negative differential conductance, on gold tips.

Cryogenic scanning tunneling microscopy and magnetization measurements were used to study the superconducting properties of ${\mathrm{MgB}}_{2}.$ The show a sharp superconductor transition at ${T}_{c}=39 \mathrm{K},$ in agreement with previous works. spectra exhibit BCS-like gap structures, parameters range 5 7 meV, yielding ratio $2\ensuremath{\Delta}{/k}_{B}{T}_{c}\ensuremath{\sim}3\ensuremath{-}4.$ This suggests that ${\mathrm{MgB}}_{2}$ is conventional BCS s-wave superconductor, either...

We report a scanning tunneling spectroscopy investigation of polycrystalline ${\text{SmFeAsO}}_{0.85}$ having superconducting transition at 52 K. On large regions the sample surface spectra exhibited $\mathrm{V}$-shaped gap structures with no coherence peaks, indicating degraded properties. In some regions, however, peaks were clearly observed and gaps could be fitted to theory into $d$-wave superconductor, yielding values between 8 8.5 meV corresponding ratio...

Considerable evidence for proximity-induced triplet superconductivity on the ferromagnetic side of a superconductor-ferromagnet (S-F) interface now exists; however, corresponding effect superconductor has hardly been addressed. We have performed scanning tunneling spectroscopy measurements NbN superconducting thin films proximity coupled to half-metallic ferromagnet La2/3Ca1/3MnO3 (LCMO) as function magnetic field. found that at zero and low applied fields spectra typically show an anomalous...

Scanning tunneling spectroscopy measurements performed on La${}_{0.7}$Ca${}_{0.3}$Mn${}_{3}$O (LCMO) films epitaxially grown Pr${}_{1.85}$Ce${}_{0.15}$CuO${}_{4}$ (PCCO) reveal localized penetration of superconductivity into the LCMO up to distances much larger than is possible for Cooper pairs in a singlet spin state exist. This long-range proximity effect manifested spectra as gaps and, less abundantly, zero-bias conductance peaks (ZBCPs). Since ZBCPs were not found bare PCCO films, their...

A new approach for doping of Cu2S nanocrystal arrays using thermal treatment at moderate temperatures (T < 400 K) is presented. This process yields conductance enhancement by 6 orders magnitude. Local probe measurements prove this an intraparticle effect and, moreover, tunneling spectroscopy data signify p-type doping. The mechanism attributed to Cu vacancy formation, resulting in free holes. Thermal-doping temperature dependence exhibits Arrhenius-like behavior, providing the formation...