We examine the efficacy of Dark-mode plasmonics as a platform for enhanced magneto-optics. Dark-mode of a small particle consists of two co-existing equal-intensity and mutually opposing dipolar excitations. Each of these two opposing dipoles may even resonate at or near the dark-mode frequency , but the net dipole moment vanishes due to the mutual cancelation between the opposing dipoles. We show that application of external magnetic bias may alleviate the intense destructive interference. Furthermore, under external magnetic bias the opposing dark-resonances of a plasmonic particle shift in opposite directions and create a region of extremely sensitive Faraday rotation. We show that the magnetized dark resonance in lossless Ag-like particle may provide more than 20 degrees rotation under magnetic fields of the order of 1-2 Tesla, exhibiting magneto-plasmonic activity that is 2-3 orders of magnitude larger than that observed in conventional plasmonic particle of the same material. 1 Dark modes of an open optical structure can be described as states of excitations that incorporate mutually opposing local dipoles whose far-fields interfere destructively. The net dipolar excitation then vanishes, resulting in a significant reduction of the far-field radiation, and consequently a reduction of the associated radiation damping and bandwidth. 1-8 This, in turn, may trap optical fields in a structure that is inherently coupled to a continuum. More formally, dark modes can be viewed as manifestations of discrete eigenvalues embedded within the continuous spectrum of the associated non-compact scattering operator. Dark modes were suggested as candidates for electromagnetic energy storage, enhanced biological and chemical sensors , and nanoscale waveguides. These modes can be supported by simple structures such as nano-dimers (see, e.g. the "anti-bonding" plasmons in Ref. [ 1]), trimers, 6 clustered nano-rods 3 and spheres. 7,8 In a seemingly unrelated research endeavor, nonreciprocal magneto-optics and its implementation for one-way waveguides, optical isolators and circulators, and Faraday rotators, have been under intensive study. 9-14 Currently the major drawback of nonreciprocal magneto-optics is the requirement for strong magnetic bias B 0. Efforts to reduce B 0 for various applications (e.g. Faraday polarization rotation) in plasmonic structures can be found, e.g. in. 15-17 The work in 15 reports on an experimental evidence for a 2-3 fold enhancement of magneto-optical activity in coated nano-particles. The efforts in 16,17 are limited to graphene metasurfaces. Here we study the effect of bias magnetization on plasmonic particle dark modes, and explore its potential applications as a new platform for non-reciprocal optics. As a simple and physically transparent test-case, we consider the core-shell spherical particle shown in Fig. 1, made of two plasmonic materials with close, but not identical , plasma frequencies. The structure is excited by a linearly polarized local field E L (r) = ˆ zE L e iky. When properly d...

Defects exist in almost all materials and defect engineering at the atomic level is part of modern semiconductor technology. Defects and their long-range strain fields can have a negative impact on the host materials. In materials with confined dimensions, the influence of defects can be even more pronounced due to the enhanced relative volume of the 'defective' regions. Here we report the dislocation-induced polarization instability of (001)-oriented Pb(Zr(0.52)Ti(0.48))O(3) (PZT) nanoislands, with an average height of approximately 9 nm, grown on compressive perovskite substrates. Using quantitative high-resolution electron microscopy, we visualize the strain fields of edge-type misfit dislocations, extending predominantly into a PZT region with a height of approximately 4 nm and width of approximately 8 nm. The lattice within this region deviates from the regular crystal structure. Piezoresponse force microscopy indicates that such PZT nanoislands do not show ferroelectricity. Our results suggest that misfit engineering is indispensable for obtaining nanostructured ferroelectrics with stable polarization.

In ballistic thermal conduction, the wave characteristics of phonons allow the transmission of energy without dissipation. However, the observation of ballistic heat transport at room temperature is challenging because of the short phonon mean free path. Here we show that ballistic thermal conduction persisting over 8.3 µm can be observed in SiGe nanowires with low thermal conductivity for a wide range of structural variations and alloy concentrations. We find that an unexpectedly low percentage (∼0.04%) of phonons carry out the heat conduction process in SiGe nanowires, and that the ballistic phonons display properties including non-additive thermal resistances in series, unconventional contact thermal resistance, and unusual robustness against external perturbations. These results, obtained in a model semiconductor, could enable wave-engineering of phonons and help to realize heat waveguides, terahertz phononic crystals and quantum phononic/thermoelectric devices ready to be integrated into existing silicon-based electronics.

Topological surface states in PbTaSe2 show fully gapped superconductivity, making it a potential topological superconductor.

A procedure for the selective surface functionalization of the mesopores and micropores of mesoporous silica SBA-15 has been developed. The resulting bifunctional material has been used to incorporate Pd nanoparticles in the micropores. The method described provides a general route for creating different local environments within the nanometer-sized pore structure and for the selective deposition of guest species in the micropores of this type of bimodal porous materials.

Chemical mapping at atomic-column resolution by energy-dispersive x-ray spectroscopy in a spherical aberration-corrected scanning transmission electron microscope (STEM) has been demonstrated for the 1.47-A dumbbell structure in InGaAs. The structural imaging and the chemical information in the two-dimensional map are directly correlated. Comparisons with the other existing mapping techniques of STEM in conjunction with electron energy-loss spectroscopy were discussed from aspects of ionization interactions.

Using atomically resolved electron energy-loss spectroscopy, the atomic-plane-by-atomic-plane, unit-cellby-unit-cell stoichiometry, and charge characteristics of the oxide interface (Nd 0.35 Sr 0.65)MnO 3 /SrTiO 3 , with a primitive polar discontinuity of (Nd 0.35 Sr 0.65 O) 0.35+-(TiO 2) 0 , were thoroughly investigated. (Nd 0.35 Sr 0.65)MnO 3 is a strongly correlated insulator and the interface was characterized to be insulating. The cell-specific stoichiometric evaluation unveiled an extensive interdiffusion across the interface. The plane-specific charge characterization revealed that the interdiffusion grades the primitive polar discontinuity. Despite the graded polar discontinuity, a charge transfer inversely into (Nd 0.35 Sr 0.65)MnO 3 was firmly resolved with a length scale of ∼2 nm and a charge density on the order of ∼10 13 /cm 2 and is effectively mediated by an asymmetric Ti interdiffusion. The intricate electronic correlations of the interfacial (Nd 0.35 Sr 0.65)MnO 3 unit cells and the interdiffusion-induced chemical disorder tend to render the charges localized, resulting in a localized two-dimensional electron density and thus the insulating interface, in distinct contrast to the conventional understanding of a vanishing charge density for an insulating interface and the metallic two-dimensional electron gas found at other classical polar-discontinuous interface systems. A potential strain manipulation on the electronic localization of the electron density was also proposed.

In order to determine the fatigue-free origin of the ferroelectric Bi3.25La0.75Ti3O12, a series of x-ray photoelectron spectroscopy and high resolution electron microscopy studies were performed on the polycrystalline Bi4−xLaxTi3O12 (BLTx, x=0, 0.5, 0.75, 1.0, 1.5, and 2.0) powders. From the XPS study, the surfaces of all La-containing compounds are found to consist of one outermost Bi-rich region and followed by a La-rich region, instead of the chemical stoichiometry in the bulk. An HREM study on Bi3.25La0.75Ti3O12 further confirms that this surface configuration arises from some intergrowth defects with a thickness of 5 nm appearing on the crystal edge, which is also observed in compounds with x=1.0 and 2.0, but not in the poor fatigue-resistant Bi4Ti3O12 (x=0). This La-induced defect locally changes the chemical composition of the crystal surface, which probably possesses a different physical characteristic as compared to the bulk. Consequently, it could can be the physical nature of the interface, when in contact with the metal electrode, Pt, in ferroelectric nonvolatile memory. Since the fatigue phenomenon on a ferroelectric capacitor arises predominately from the pinning of domain walls on the metal-ferroelectric interface, the surface configurations of La-containing Bi4Ti3O12 compounds should be considered as one of the fatigue-free factors as well as the self-regulation of the Bi2O2 layer and the chemical stability of the perovskite slabs. In addition, the band gap of Bi3.25La0.75Ti3O12 is also estimated by UV absorption spectrum to be 3.9±0.1 eV.