Electron relaxation in a GaAs quantum dot is investigated to second order electron-phonon interactions. Calculation of rate, as function level separation, indicates the significant contribution LO\ifmmode\pm\else\textpm\fi{}LA processes, which create window rapid (subnanosecond) around longitudinal-optical phonon energy. This result may provide possible solution problem photoluminescence degradation small dots.

We report naturally occurring van der Waals heterostructural single crystals with intrinsic magnetic topological properties.

To understand the energy relaxation of electrons interacting with both longitudinal-optical (LO) and longitudinal-acoustic (LA) phonons in a semiconductor quantum dot, electron density-of-states $D(E)$ is calculated using Green's-function method taking into account interactions all orders self-consistent level broadening. The for GaAs dot exhibits sharp peaks (width $\ensuremath{\lesssim}$ 0.1 meV ) at $T=77$ K, indicating absence fast usual sense. For separation near, but not necessarily...

The electronic band structure of the first-stage potassium-graphite intercalation compound C 8 K was calculated by a semi-empirical tight-binding scheme. Fermi surfaces can be classified into two distinct types. One is potassium-like and nearly isotropic; other carbon-like cylindrical shape. In addition, portions show nesting property, which likely to induce charge-density-wave instability. isotropic are responsible for large reduction anisotropy in conductivity relative graphite. density...

Inspired by the recent demonstration that Ca2N is a two-dimensional electride in which electrons near Fermi level float between ionic layers, we have conducted systematic search for 2D electrides an approach combining crystal structure databases and ab initio electronic calculations. Starting from set of working hypotheses, identified six metallic electrides, one nonmagnetic five are nearly ferromagnetic ferrimagnets with distinct spin texture. The latter materials first magnetic reported at...

Electrides-compounds in which electrons localized interstitial spaces periodically serve as anions-have attracted broad attention for their exotic properties, such extraordinary electron-donating ability. In our efforts to expand this small family of phases, LaScSi emerges a promising candidate. Its electron count is 2e- f.u.-1 excess that expected from the Zintl concept, while its structure offers can accommodate these extra electrons. Herein, potential explored through density functional...

Abstract In the field of photonics, alkali copper(I) halides attract considerable attention as lead‐free emitters. The intrinsic quantum confinement effects originating from low‐dimensional electronic structure lead to high photoluminescence yields (PLQYs). Among them, Cs 3 Cu 2 I 5 is most promising candidate, satisfying both PLQY and air stability. this study, a strategy explore new material meeting these requirements through use mixed‐anions − Cl proposed. expectation maintained that...

The radiative decay of one-dimensional (1D) excitons is studied in novel GaAs quantum wires (QWI's) prepared by molecular beam epitaxy. temperature dependence the lifetime \ensuremath{\tau}(T) measured, and compared with that 2D wells (QW's): 1D grows much more slowly T than excitons, resulting shorter for T>20 K. This ascribed to thermalization concentrated density states QWIs. Analysis based on a theory has revealed expressed as 92\ensuremath{\surd}T ps...

A ridge quantum wire structure has been successfully fabricated on a patterned (001) GaAs substrate by first growing (111)B facet with very sharp and then depositing thin well its top. Electron microscope study shown that the effective lateral width of 17–18 nm is formed at Photoluminescence cathodoluminescence measurements indicate one luminescence lines comes from region blue shift (∼60 meV) agrees confined energy calculated for observed structure.

We have probed the internal structure and nonlinear response of magnetoexcitons in GaAs/AlGaAs quantum wells by resonantly driving one- two-photon transitions with intense terahertz electric fields. Strong near-band-gap emission lines, or optical sidebands, appear at frequencies ${\ensuremath{\omega}}_{\mathrm{NIR}}\ifmmode\pm\else\textpm\fi{}2n{\ensuremath{\omega}}_{\mathrm{THz}}$, where ${\ensuremath{\omega}}_{\mathrm{NIR}}$ is interband exciton-creation frequency,...

We reported LnRuSi as a B₅-site-free Ru catalyst for ammonia synthesis, and its activity enhanced 2–4-fold by selective etching with EDTA-2Na.

Abstract Electrides loaded with transition‐metal (TM) nanoparticles have recently attracted attention as emerging materials for catalytic NH 3 synthesis. However, they suffer from disadvantages associated the growth and aggregation of nanoparticles. TM‐containing intermetallic electrides appear to be promising catalysts advantages both transition metals in a single phase. LaRuSi is reported here an electride superior activity synthesis, direct evidence provided supporting its...

The electronic structure of the superatom, a recently proposed mesoscopic system made spherical semiconductor heterostructure, is investigated by self-consistent local-density-functional calculation. Numerical results on AlGaAs-GaAs superatoms reveal that atomic-orbital picture can be successfully applied and ground-state configuration stable at $T\ensuremath{\sim}1$ K. level structure, however, quite distinct from ordinary atoms because absence $\frac{1}{r}$ singularity in potential.

Ab initio electronic structure calculations show that the recently identified quasi-two-dimensional electride ${\mathrm{Y}}_{2}\mathrm{C}$ is a weak itinerant ferromagnet or at least close to ferromagnetic instability. The ferromagnetism induced by electrons, which are loosely bound around interstitial sites and overlap with each other form two-dimensional interlayer conduction bands. semimetallicity two-dimensionality of band keys understanding this

Electron transport through a multilevel quantum dot with intradot Coulomb repulsion is discussed theoretically. Based on the calculated local density of states, we argue that characteristic peaks should be seen in differential conductance if has group closely spaced levels. These provide hallmark Kondo-type correlation. Our proposal especially pertinent one realizes Kondo temperature system may enhanced by orders magnitude over for single-level system.

GaAs quantum wells are simultaneously illuminated with near-infrared (NIR) radiation at frequency ωnir and intense far-infrared (FIR) from a free-electron laser ωfir. Magnetic fields up to 9 T applied. Strong narrow sidebands observed ωsideband=ωnir±2ωfir. The intensity of the is enhanced when either ωsideband or near onset NIR absorption in well, ωfir cyclotron frequency. We attribute these four-wave mixing FIR photons whose energies differ by more than factor 100.

Pentacene/tetracene organic superlattices were formed by deposition on a glass substrate, and their structure was investigated x-ray diffraction photoluminescence. For samples in which the number (n) of constituent pentacene (or tetracene) molecular layers within period is such that n≥3, first-order peak found to consist several equally spaced subpeaks. Comparison spectra with calculated factors established well-defined superlattice achieved these samples. In contrast, n<3 showed no...

The first investigation of the lattice dynamics In1−xGaxAsyP1−y quaternary semiconductor alloys matched to GaAs has been made by Raman scattering. spectra in optical frequency range consist two separate bands, each having a peak at high-frequency end. These peaks are shown be GaP-like and GaAs-like, respectively. cell-isodisplacement theory for long-wavelength Zinger, Ipatova, Subashiev [Sov. Phys. Semicond. 10, 286 (1976)] is reexamined detail. It improved upon consistently treating...

Compounds having excess electrons from the formal valence viewpoint (electrides) are a new class of materials, which often take low-dimensional structures. We studied (001) surface electronic structures quasi-two-dimensional electrides ${\mathrm{Ca}}_{2}\mathrm{N}$ and ${\mathrm{Y}}_{2}\mathrm{C}$ by density functional theory using slab model. Both materials were found to have clean state well separated in energy bulk states. Furthermore, this virtually floats above may be considered...

Two-dimensional (2D) electrides are a new concept material in which anionic electrons confined the interlayer space between positively charged layers. We have carried out angle-resolved photoemission spectroscopy measurements on ${\mathrm{Y}}_{2}\mathrm{C}$, is possible 2D electride, order to verify formation of electride states ${\mathrm{Y}}_{2}\mathrm{C}$. clearly observe existence semimetallic ``electride bands'' near Fermi level, as predicted by ab initio calculations, conclusively...

In the search for stable topological semimetals with clean band profiles, we have screened all 3$d$ metal-intercalated transition-metal dichalcogenides (3dI-TMDCs) by performing hybrid-functional-based ab initio calculations. Two classes of materials featuring twelve Weyl nodes in $k_z=0$ plane (without spin-orbit interactions) are identified: (a) time-reversal-breaking VT$_3$X$_6$ (ferromagnetic) and (b) spinless MnT$_3$X$_6$ (nonmagnetic), where T=Nb, Ta; X=S, Se. VNb$_3$S$_6$,...

Over the last half century, layered materials have been at forefront of science, spearheading discovery new phenomena and functionalities. Certain are known to possess electronic states unassociated with any constituent atoms, having a large proportion their probability amplitude in space between layers. Usually, such nucleus‐free interlayer state has energy above Fermi level is unoccupied. However, decreases when cations intercalated may cross level, as case C 6 Ca, superconductor T c 11.5...

An electronic structure calculation for the novel quantum wire recently fabricated and named ‘‘ridge wire’’ [Koshiba et al., Appl. Phys. Lett. 64, 363 (1994)] is reported. In calculation, actual confinement potential was approximated by an analytic model, which considerably facilitates solution of Schrödinger equation finite element method. The result clearly indicates strong both electrons holes. Also quantization energy obtained, with exciton effects included, in good agreement...

In some metals, the resistivity goes up when temperature is lowered, instead of going down. This unusual phenomenonon called Kondo effect after its discoverer who explained it in bulk metals more than 60 years ago. his Perspective, Inoshita discusses recent results from groups at Massachusetts Institute Technology, Weizmann Institute, and Delft University which has been observed single-electron quantum dot structures. The new findings support theoretical predictions establish a system for...