Monodisperse Er(3+):NaGdF(4)@Ho(3+):NaGdF(4)@NaGdF(4) active-core/active-shell/inert-shell nanocrystals, which can extend the near-infrared wavelength excitable range for upconversion (UC) emissions, were successfully fabricated for the first time. Importantly, doping of Er(3+) and Ho(3+) into the core and shell respectively suppresses adverse energy transfers between them, resulting in intense UC emissions for both Er(3+) and ...

A series of upconversion luminescent erbium-doped SrTiO(3) (ABO(3) -type) photocatalysts with different initial molar ratios of Sr/Ti have been prepared by a facile polymerized complex method. Er(3+) ions, which were gradually transferred from the A to the B site with increasing Sr/Ti, enabled the absorption of visible light and the ...

Silica-graphene oxide (Si-GO) hybrid composite particles were prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of hydrophilic GO obtained from a modified Hummers method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images provided visible evidence of the silica nanoparticles grafted on the surface of GO, ...

The electroluminescence (EL) at 1.54 µm of metal-oxide-semiconductor (MOS) devices with Er(3+) ions embedded in the silicon-rich silicon oxide (SRSO) layer has been investigated under different polarization conditions and compared with that of erbium doped SiO(2) layers. EL time-resolved measurements allowed us to distinguish between two different excitation mechanisms responsible for ...

Reduced graphenes (belonging to the class of chemically modified graphenes, CMG) are one of the most investigated and utilized materials in current research. Oxygen functionalities on the CMG surfaces have dramatic influences on material properties. Interestingly, these functionalities are rarely comprehensively characterized. Herein, the four most commonly used CMGs, mainly ...

Three types of high-quality, monodisperse lanthanide fluoride colloidal nanocrystals (NCs) including LnF(3) (Ln = La-Pr), NaLnF(4) (Ln = Sm-Er), and Na(5)Ln(9)F(32) (Ln = Tm-Lu) with two crystal phases (hexagonal and cubic) and a rich variety of morphologies have been synthesized in high boiling organic solvents oleic acid and 1-octadecene, via ...

Monodisperse oleic acid stabilized pure NaYF(4) nanoparticles with controlled size and shape have been successfully synthesized by changing the initial reaction temperature. Transparent nanocomposite thin films consisting of NaYF(4):Yb, Er (Tm) upconverting nanoparticles (UCNPs) and fluorocarbon resin (FC) are deposited on the slide glass by dip-coating method. The results show ...

Stimulated by recent experimental discoveries, triaxial strongly deformed (TSD) states in ^{158}Er at ultrahigh spins have been studied by means of the Skyrme-Hartree-Fock model and the tilted-axis-cranking method. Restricting the rotational axis to one of the principal axes-as done in previous cranking calculations-two well-defined TSD minima in the total Routhian ...

A stable dispersion of multifunctional Gd(2) O(3) :Er,Yb phosphor in polyvinyl alcohol (PVA) was synthesized by varying the concentration of Yb(3+) ions. It had a strong ultraviolet-visible-near infrared (UV-vis) upconversion emission and applications in temperature and magnetic field sensors (e.g., nano-heaters), as well as potential use in bioleveling and bioimaging. ...

ABSTRACT: Size-dependent photoluminescence characteristics from Ge nanocrystals embedded in different oxide matrices have been studied to demonstrate the light emission in the visible wavelength from quantum-confined charge carriers. On the other hand, the energy transfer mechanism between Er ions and Ge nanocrystals has been exploited to exhibit the emission in ...

We measured electronic transitions of the 2D graphene-type molecule hexa-peri-hexabenzocoronene (HBC) at the single-molecule level. The large intersystem crossing rate and long triplet state lifetime in the range of seconds are prohibitive for direct single-molecule observation. By covalently coupling fluorescent acceptor molecules (perylenecarboximide, PMI) to HBC, efficient singlet energy transfer ...

ABSTRACT: GeMn/Ge epitaxial 'superlattices' grown by molecular beam epitaxy with different growth conditions have been systematically investigated by transmission electron microscopy. It is revealed that periodic arrays of GeMn nanodots can be formed on Ge and GaAs substrates at low temperature (approximately 70degreesC) due to the matched lattice constants of ...

Electronic structures of well-aligned Er-doped ZnO (ZnO:Er) nanorod arrays (NRAs) synthesized by a solution-based hydrothermal process were characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray absorption fine structure (XAFS). HRTEM and angular dependent X-ray absorption near-edge structure analysis at O K and Zn L3 edges indicates that the spontaneous ...

Photoluminescence properties of the Er(3+)-Dy3+ codoped tellurite glasses were studied by absorption and visible emission spectra, which revealed luminescence bands of both Er3+ and Dy3+ when pumping with the wavelength of 325 nm. The concentration quenching occurred as Dy3+ concentration increased beyond 3 mol%. The dependence of Er3+ characteristic emission ...

A series of dipolar and octupolar triphenylamine-derived dyes containing a benzothiazole positioned in the matched or mismatched fashion have been designed and synthesized via palladium-catalyzed Sonogashira cross-coupling reactions. Linear and nonlinear optical properties of the designed molecules were tuned by an additional electron-withdrawing group (EWG) and by changing the relative ...

We introduce a novel method for local structure determination with a spatial resolution of the order of 0.01 Å. It can be applied to materials containing clusters of exchange-coupled magnetic atoms. We use neutron spectroscopy to probe the energies of the cluster excitations which are determined by the interatomic coupling strength ...

Lattice match is important for epitaxial growth. We show that a competing mechanism, electronic match, can dominate at small film thicknesses for metal-semiconductor systems, where quantum confinement and symmetry requirements may favor a different growth pattern. For Pb(111) on Ge(111), an accidental lattice match leads to a sqrt[3]×sqrt[3] configuration involving ...

In the last 40 years, low energy electron diffraction (LEED) has proved to be the most reliable quantitative technique for surface structural determination. In this review, recent developments related to the theory that gives support to LEED structural determination are discussed under a critical analysis of the main theoretical approximation-the ...

An efficient algorithm is developed to construct disconnectivity graphs by a random walk over basins of attraction. This algorithm can detect a large number of local minima, find energy barriers between them, and estimate local thermal averages over each basin of attraction. It is applied to the Sherrington-Kirkpatrick (SK) spin ...

An understanding of why adenine (A) pairs with thymine (T) and cytosine (C) with guanine (G) in DNA is very useful in the design of sensors and other related devices. We report the use of dissociation energies, geometries and molecular electrostatic potentials (MEPs) to justify the canonical (AT and CG) ...

Trianionic spin-quartet and tetraanionic spin-quintet molecular clusters derived from m-dibenzoylbenzene in solution were identified by CW-ESR/pulse-ESR based two-dimensional electron spin transient nutation spectroscopy, and their spin and clustering structures in the ground state were determined in terms of a D-tensor based phenomenological approach and DFT calculations. The molecular structures obtained ...

Effects of scalar spin-spin interactions on the nuclear magnetic relaxation dispersion (NMRD) of coupled multispin systems were analyzed. Taking spin systems of increasing complexity we demonstrated pronounced influence of the intramolecular spin-spin couplings on the NMRD of protons. First, at low magnetic fields where there is strong coupling of spins ...

Coherent control of OH-free radicals interacting with the spin-triplet state of a DNA molecule is investigated. A model Hamiltonian for molecular spin singlet-triplet resonance is developed. We illustrate that the spin-triplet state in DNA molecules can be efficiently populated, as the spin-injection rate can be tuned to be orders of ...

The manipulation of the electron spin degree of freedom is at the core of the spintronics paradigm, which offers the perspective of reduced power consumption, enabled by the decoupling of information processing from net charge transfer. Spintronics also offers the possibility of devising hybrid devices able to perform logic, communication, ...

The pure rotational spectrum of the CrS radical has been measured in its ground X (5)Π(r) state using gas-phase millimeter/submillimeter direct absorption methods. The molecule was created by the reaction of chromium vapor, sublimed in a Broida-type oven, with hydrogen sulfide. Eleven rotational transitions were recorded for this free radical ...

Spin dynamics under magic angle spinning has been studied using different theoretical approaches and also by extensive numerical simulation programs. In this article we present a general theoretical approach that leads to analytic forms for effective Hamiltonians for an N-spin dipolar and quadrupolar coupled system under magic angle spinning (MAS) ...

Here, we predict that the ferromagnetically coupled cobalt-benzene-cobalt system will act as the smallest molecular spin filter with unprecedented spin injection coefficient. To validate our in-silico observation, we have performed state-of-the-art nonequilibrium Green's function calculations and analyzed the density of states of cobalt at the relativistic and nonrelativistic level of ...

In dynamic nuclear polarization (DNP) experiments applied to organic solids for creating nonequilibrium, high (1)H spin polarization, an efficient buildup of (1)H polarization is attained by partially deuterating the material of interest with an appropriate (1)H concentration. In such a dilute (1)H spin system, it is shown that the (1)H ...

On the basis of the zero-temperature grand canonical ensemble generalization of the energy E[N,N(s),v,B] for fractional particle N and spin N(s) numbers, the energy surface over the (N,N(s)) plane is displayed and analyzed in the case of homogeneous external magnetic fields B(r). The (negative of the) left-/right-side derivatives of the ...

The exceptional spin coherence of nitrogen-vacancy centers in diamond motivates their function in emerging quantum technologies. Traditionally, the spin state of individual centers is measured optically and destructively. We demonstrate dispersive, single-spin coupling to light for both nondestructive spin measurement, through the Faraday effect, and coherent spin manipulation, through the ...

Organic semiconductors offer expansive grounds to explore fundamental questions of spin physics in condensed matter systems. With the emergence of organic spintronics and renewed interest in magnetoresistive effects, which exploit the electron spin degree of freedom to encode and transmit information, there is much need to illuminate the underlying properties ...

Zero-field splitting (ZFS) tensors (D tensors) of organic high-spin oligonitrenes/oligocarbenes up to spin-septet are quantitatively determined on the basis of quantum chemical calculations. The spin-orbit contributions, D(SO) tensors are calculated in terms of a hybrid CASSCF/MRMP2 approach, which was recently proposed by us. The spin-spin counterparts, D(SS) tensors are computed ...

Some specific designs on the electron blocking layer (EBL) of blue InGaN LEDs are investigated numerically in order to improve the hole injection efficiency without losing the blocking capability of electrons. Simulation results show that polarization-induced downward band bending is mitigated in these redesigned EBLs and, hence, the hole injection ...

Room temperature electronic diffusion is studied in 3 μm thick epitaxial p(+) GaAs lift-off films using a novel circularly polarized photoluminescence microscope. The method is equivalent to using a standard optical microscope and provides a contactless means to measure both the charge (L) and spin (L(s)) diffusion lengths simultaneously. The measured ...

First-principles and non-equilibrium Green's function approaches are used to predict spin-polarized electronic transport in monatomic carbon chains covalently connected to graphene nanoribbons, as recently synthetized experimentally (Jin, C.; et al. Phys. Rev. Lett. 2009, 102, 205501-205504). Quantum electron conductances exhibit narrow resonant states resulting from the simultaneous presence of open ...

The size of silicon transistors used in microelectronic devices is shrinking to the level at which quantum effects become important. Although this presents a significant challenge for the further scaling of microprocessors, it provides the potential for radical innovations in the form of spin-based quantum computers and spintronic devices. An ...

Thermoelectric generation is an essential function in future energy-saving technologies. However, it has so far been an exclusive feature of electric conductors, a situation which limits its application; conduction electrons are often problematic in the thermal design of devices. Here we report electric voltage generation from heat flowing in an ...

Reducing the heat generated in traditional electronics is a chief motivation for the development of spin-based electronics, called spintronics. Spin-based transistors that do not strictly rely on the raising or lowering of electrostatic barriers can overcome scaling limits in charge-based transistors. Spin transport in semiconductors might also lead to dissipation-less ...

Single spins in solid-state systems are often considered prime candidates for the storage of quantum information, and their interaction with the environment the main limiting factor for the realization of such schemes. The lifetime of an excited spin state is a sensitive measure of this interaction, but extending the spatial ...

Exact analysis of spin crossover in infinite elastic chain of two-spin exchange clusters was performed theoretically beyond mean-field approximation. Statistical mechanics of the system was exactly calculated by means of the transfer matrix technique. A possibility of spin-Peierls-like magneto-structural transition in a one-dimensional chain was shown as a result of ...

The use of supramolecular architectures to control the spatially dependent spin exchange (spin communication) between two covalently linked radical centers (biradical) has been explored. Cucurbit[8]uril, through supramolecular steric effect, completely suppresses spin exchange between two adjacent radical centers in a biradical.

In systems with strong spin-orbit coupling, the relationship between spin transfer torque and the divergence of the spin current is generalized to a relation between spin transfer torques, total angular momentum current, and mechanical torques. In ferromagnetic semiconductors, where the spin-orbit coupling is large, these considerations modify the behavior of ...

Spin relaxation of two-dimensional electrons in a GaAs/AlGaAs quantum well was studied by time-resolved Kerr rotation measurements using a two-color pump and probe technique. In quantum Hall ferromagnets, the spin-wave relaxation is strongly influenced by the photogenerated Skyrmion and anti-Skyrmion pairs. By tuning the pump and probe lights to the ...

We show how in ultracold Fermi gases the difference between the finite temperature T structure factors, called S_(ω,q), associated with spin and density, reflects coherent order at all ω, q, k(F)a, and T. This observation can be exploited in two photon Bragg scattering experiments on gases which are subject to ...

This paper is devoted to multiple quantum (MQ) NMR spectroscopy in nanopores filled by a gas of spin-carrying molecules (s = 1/2) in a strong external magnetic field. It turns out that the high symmetry of the spin system in nanopores yields a possibility to overcome the problem of the ...

Electrical injection of spin-polarized electrons into a semiconductor, large spin diffusion length, and an integration friendly platform are desirable ingredients for spin-based devices. Here we demonstrate lateral spin injection and detection in germanium nanowires, by using ferromagnetic metal contacts and tunnel barriers for contact resistance engineering. Using data measured from ...

We study the effect of coupling magnetic impurities to the honeycomb lattice spin-1/2 Kitaev model in its spin-liquid phase. We show that a spin-S impurity coupled to the Kitaev model is associated with an unusual Kondo effect with an intermediate coupling unstable fixed point Kc∼J/S separating topologically distinct sectors of ...

An investigation into spin structures of poly(m-phenylenecarbene), a prototype of magnetic organic molecules, is presented using the ab initio density matrix renormalization group method. It is revealed by achieving large-scale multireference calculations that the energy differences between high-spin and low-spin states (spin-gaps) of polycarbenes decrease with increasing the number of ...

An extensive redistribution of spin density in TBrPP-Co molecules adsorbed on a Cu(111) surface is investigated by monitoring Kondo resonances at different locations on single molecules. Remarkably, the width of the Kondo resonance is found to be much larger on the organic ligands than on the central cobalt atom-reflecting enhanced ...

The concept of a ponderomotive force due to the intrinsic spin of electrons is developed. An expression containing both the classical as well as the spin-induced ponderomotive force is derived. The results are used to demonstrate that an electromagnetic pulse can induce a spin-polarized plasma. Furthermore, it is shown that, ...