Materials Literature
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We study the dynamics of magnetization coupled to a thermal bath of elastic modes using a system plus reservoir approach with realistic magnetoelastic coupling. After integrating out the elastic modes we obtain a self-contained equation for the dynamics of the magnetization. We find explicit expressions for the memory…
We have investigated the electronic structure of the equiatomic EuAuMg, GdAuMg, YbAuMg and GdAgMg intermetallics using x-ray photoelectron spectroscopy. The spectra revealed that the Yb and Eu are divalent while the Gd is trivalent. The spectral weight in the vicinity of the Fermi level is dominated by the mix of Mg $…
We study magnetization reversal using various r.f. magnetic pulses. We show numerically that switching is possible with simple sinusoidal pulses; however the optimum approach is to use a frequency-swept (chirped) r.f. magnetic pulse, the shape of which can be derived analytically. Switching times of the order of nanos…
Nonlinear optics: Twisted π-electron system electrooptic (EO) chromophores with exceptional molecular hyperpolarizabilities (−488 000×10−48 esu at 1907 nm) were designed and synthesized. Crystallographic analysis reveals large twist angles and a highly charge-separated zwitterionic ground state. Experiments on poled h…
Further development of a previously introduced method for numerically simulating magnetic spin waves is presented. Together with significant improvements in speed, the method now allows one to calculate the energy absorbed by the various modes excited by a position- and time-dependent H1 field in a ferromagnetic body…
The Eu-based compound, $\mathrm{Eu}{\mathrm{Cu}}_{2}{\mathrm{As}}_{2}$, crystallizing in the $\mathrm{Th}{\mathrm{Cr}}_{2}{\mathrm{Si}}_{2}$-type tetragonal structure, has been synthesized and its magnetic behavior has been investigated by magnetization $(M)$, heat-capacity $(C)$, and electrical resistivity $(\ensurem…
Advances in solid-state device design now allow the spectrum of transmitted electrons in thermionic and thermoelectric devices to be engineered in ways that were not previously possible. Here we show that the shape of the electron energy spectrum in these devices has a significant impact on their performance. We disti…
We devise an inverse statistical-mechanical methodology to find optimized interaction potentials that lead spontaneously to a target many-particle configuration. Target structures can possess varying degrees of disorder, thus extending the traditional idea of self-assembly to incorporate both amorphous and crystalline…
The magnetically induced martensitic variant reorientation process under applied mechanical load in magnetic shape memory alloys (MSMAs) is considered. Of particular interest is the associated nonlinear and hysteretic macroscopic strain response under variable applied magnetic field in the presence of stress, also kno…
We demonstrate that very few (1 to 3) quantum dots as a gain medium are sufficient to realize a photonic crystal laser based on a high-quality nanocavity. Photon correlation measurements show a transition from a thermal to a coherent light state proving that lasing action occurs at ultra-low thresholds. Observation of…
Magnetization reversal (switching) using either r.f. fields or brute-force precessional switching is currently thought to ultimately be limited by the non-linear excitation of non-uniform spin waves, the so-called Suhl instability. Here we show (numerically, for the case of a sphere) that this instability can be suppr…
Recently developed eigenvalue method is being used to calculate absorption spectra in magnetic square nanodots and nanodisks. Obtained results are being compared with both theoretical and experimental results obtained previously for such structures.
Basis set convergence of the Hartree-Fock and the correlation energy is examined for the hydrogen bonded infinite bent chains (HF)_infinity and (HCl)_infinity. We employ series of correlation consistent basis sets up to quintuple zeta quality together with a coupled cluster method (CCSD) to describe electron correlati…
We report electrical transport experiments, using the phenomenon of electrical breakdown to perform thermometry, that probe the thermal properties of individual multiwalled carbon nanotubes. Our results show that nanotubes can readily conduct heat by ballistic phonon propagation. We determine the thermal conductance q…
We present a detailed magnetic study of the ${\mathrm{Pr}}_{1∕3}{\mathrm{Ca}}_{2∕3}\mathrm{Mn}{\mathrm{O}}_{3}$ manganite, where we observe the presence of small ferromagnetic (FM) domains (diameter $\ensuremath{\sim}10\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$) immersed within the charge-ordered antiferromagnetic (AF…
Abstract Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential for applications such as electromagnetic interference shielding, magneto‐optical storage, biomedical sensing, flexible electronics, etc. Control over the dispersion of the nanoparticle p…
Recent theory has found that native defects such as the O vacancy V(O) and Zn interstitial Zn(I) have high formation energies in n-type ZnO and, thus, are not important donors, especially in comparison to impurities such as H. In contrast, we use both theory and experiment to show that, under N ambient, the complex Zn…
The hierarchical self-assembly of disc-shaped molecules leads to the formation of discotic liquid crystals. These materials are of fundamental importance not only as models for the study of energy and charge migration in self-organized systems but also as functional materials for device applications such as, one-dimen…
For the first time, stable aqueous dispersions of polymer-coated graphitic nanoplatelets can be prepared via an exfoliation/in-situ reduction of graphite oxide in the presence of poly(sodium 4-styrenesulfonate).
The interactions of Cu(II)-meso-Tetrakis(n-N-methylpyridiniumyl)porphyrin (n = 2,3,4), respectively referred to as o-, m- and p-CuTMPyP, and DNA, poly<TEX>$[d(A-T)_2]$</TEX> and poly<TEX>$[d(G-C)_2]$</TEX> were investigated by circular and linear dichroism (CD and LD). In the o-CuTMPyP case, in which the rotation of t…