Search results for "dipole"

Novel plasmonic sensor design using plasmon-induced transparency

2010

We introduce a novel sensor concept in the field of plasmonics, namely plasmon-induced transparency sensors. These sensors combine localized particle plasmon resonances with extremely small sensing volume with excellent sharp spectral resonances that show a good respose to refractive index changes of the surrounding environment. The principle is based on the plasmonic analog of electromagnetically induced transparency (EIT) between a radiative dipole and a nonradiative quadrupole antenna. This effect yields a spectrally narrow resonance within a broad localized particle plasmon resonance in the near-infrared spectral region [1, 2]. Using deposition of biotin and streptavidin, we demonstrate…

Role of Intrinsic Dipoles in the Evaporation‐Driven Assembly of Perovskite Nanocubes into Energy‐Harvesting Composites

2020

Magnetic resonance study of bulk and thin film EuTiO3

2017

Magnetic resonance spectra of EuTiO3 in both bulk and thin film form were taken at temperatures from 3-350 K and microwave frequencies from 9.2-9.8 and 34 GHz. In the paramagnetic phase, magnetic resonance spectra are determined by magnetic dipole and exchange interactions between Eu2+ spins. In the film, a large contribution arises from the demagnetization field. From detailed analysis of the linewidth and its temperature dependence, the parameters of spin-spin interactions were determined: the exchange frequency is 15-15.5 GHz and the estimated critical exponent of the spin correlation length is ~ 0.5. In the bulk samples, the spectra exhibited a distinct minimum in the linewidth at the N…

Orientational dynamics of colloidal ribbons self-assembled from microscopic magnetic ellipsoids

2016

We combine experiments and theory to investigate the orientational dynamics of dipolar ellipsoids, which self-assemble into elongated ribbon-like structures due to the presence of a permanent magnetic moment, perpendicular to the long axis in each particle. Monodisperse hematite ellipsoids are synthesized via the sol-gel technique and arrange into ribbons in the presence of static or time-dependent magnetic fields. We find that under an oscillating field, the ribbons reorient perpendicular to the field direction, in contrast with the behaviour observed under a static field. This observation is explained theoretically by treating a chain of interacting ellipsoids as a single particle with or…

Laser spectroscopy of cooled zirconium fission fragments

2002

The first on-line laser spectroscopy of cooled fission fragments is reported. The $^{\mathrm{96}\mathrm{--}\mathrm{102}}\mathrm{Z}\mathrm{r}$ ions, produced in uranium fission, were extracted and separated using an ion guide isotope separator. The ions were cooled and bunched for collinear laser spectroscopy by a gas-filled linear Paul trap. New results for nuclear mean-square charge radii, dipole, and quadrupole moments are reported across the $N=60$ shape change. The mean-square charge radii are found to be almost identical to those of the Sr isotones and previously offered modeling of the radial changes is critically reviewed.

Layered gadolinium hydroxides for low-temperature magnetic cooling

2015

Layered gadolinium hydroxides have revealed to be excellent candidates for cryogenic magnetic refrigeration. These materials behave as pure 2D magnetic systems with a Heisenberg-Ising critical crossover, induced by dipolar interactions. This 2D character and the possibility offered by these materials to be delaminated open the possibility of rapid heat dissipation upon substrate deposition.

The elastic interaction of high-spin and low-spin complex molecules in spin-crossover compounds

1988

Several transition metal compounds show a transition from the low-spin (LS) to the high-spin (HS) electronic state with increasing temperature. The cooperative nature of the transition is usually parametrised by an interaction constant Gamma , the origin of which is still under discussion. In the frame of the lattice expansion mode, the interaction Gamma is attributed to the elastic interaction between the spin-changing ions as a result of the deformation of the crystal accompanying the transition. The authors calculate the complete elastic energy originating from the so-called image pressure in closed form by considering the crystal as an isotropic homogeneous elastic medium with the spin-…

Dipoles in 4,12,4-graphyne

2021

Abstract In present work, B-N pairs as dipole source were introduced into 4,12,4-graphyne. According to the density functional theory (DFT) simulations, the electronic configurations of the doped 4,12,4-graphyne systems were significantly modified owing to the built-in electric fields caused by the B-N dipoles. Different B-N concentrations and arrangements can alter the electronic structure of 4,12,4-graphyne. Consequently, an obvious in-plane piezoelectricity can also be induced. Moreover, the direct band gap can be delicately modulated from 150 meV to 660 meV at PBE level. The B-N dipoles can also greatly enhance the light absorption instead of shifting the absorption region. According to…

Magnetic Anisotropies and Coupling Mechanisms inFe/Mo(110)Nanostripes

2005

Using low-temperature (5 K) spin-polarized scanning tunneling microscopy, we have studied the morphology and magnetic properties of monolayer (ML) and double layer (DL) thick Fe nanowires grown by step flow on a Mo(110) single crystal. Magnetic contrast has been obtained using tungsten tips covered by Au/Co thin films. We find that the DL Fe nanowires, similarly to ML Fe nanowires, are perpendicularly magnetized. Because of the dipolar coupling, separated DL Fe nanowires are antiferromagnetically coupled. DL wires that are touching at step edges are ferromagnetically ordered due to direct exchange coupling. We measured the widths of the magnetic domain walls in the ML and DL Fe nanowires. T…

Polarized neutron reflectivity from monolayers of self-assembled magnetic nanoparticles

2015

We prepared monolayers of iron oxide nanoparticles via self-assembly on a bare silicon wafer and on a vanadium film sputter deposited onto a plane sapphire substrate. The magnetic configuration of nanoparticles in such a dense assembly was investigated by polarized neutron reflectivity. A theoretical model fit shows that the magnetic moments of nanoparticles form quasi domain-like configurations at remanence. This is attributed to the dipolar coupling amongst the nanoparticles.