Search results for "FLE"
showing 10 items of 3517 documents
Effect ofA-site andB-site substitution on the infrared reflectivity spectra ofLa1−yAyMn1−xBxO3(A=Ba,Sr;B=Cu,Zn,Sc;0<y<~0.3;0<~x<~0.1)mang…
2003
We have measured the infrared reflectivity spectra of ${\mathrm{La}}_{1\ensuremath{-}y}[\mathrm{Sr}(\mathrm{Ba}){]}_{y}{\mathrm{Mn}}_{1\ensuremath{-}x}[\mathrm{Cu}(\mathrm{Zn},\mathrm{Sc}){]}_{x}{\mathrm{O}}_{3}$ $(0lyl~0.3,0l~xl~0.10)$ manganites, in a wide frequency $(100\char21{}4000{\mathrm{cm}}^{\ensuremath{-}1})$ and temperature (80 K\char21{}300 K) range. The reflectivity spectra were analyzed by a fitting procedure based on a model that includes Drude, midinfrared electronic, and phonon oscillator contributions to the dielectric constant. Six infrared active ${(3A}_{u}$ and ${3E}_{u})$ modes of rhombohedral symmetry are clearly observed. We assigned all observed modes according to e…
Neutron Scattering in Nanomagnetism
2015
Abstract Polarized neutron reflectometry (PNR) has played an essential role for the exploration of nanomagnetic and spintronic materials, including exchange coupled magnetic superlattices, exchange bias systems between ferromagnetic and antiferromagnetic films, spin valves, exchange springs between soft and hard magnetic films, superconducting proximity effects, periodic lateral magnetic patterns, and magnetic nanoparticles. The main virtues of PNR are depth-resolved vector magnetometry in the film plane, high sensitivity to magnetic interfaces, and statistical analysis of magnetic domain fluctuations. Recently the capabilities of PNR have been carried over from steady state to dynamic inve…
On the half-metallicity of Co2FeSi Heusler alloy: Point-contact Andreev reflection spectroscopy andab initiostudy
2013
Co2FeSi, a Heusler alloy with the highest magnetic moment per unit cell and the highest Curie temperature, has largely been described theoretically as a half-metal. This conclusion, however, disagrees with point contact Andreev reflection (PCAR) spectroscopy measurements, which give much lower values of spin polarization, P. Here, we present the spin polarization measurements of Co2FeSi by the PCAR technique, along with a thorough computational exploration, within the DFT and a GGA+U approach, of the Coulomb exchange U parameters for Co and Fe atoms, taking into account spin-orbit coupling. We find that the orbital contribution (mo) to the total magnetic moment (mT) is significant, since it…
Kinks and antikinks of buckled graphene: A testing ground for phi^4 field model
2017
Kinks and antikinks of the classical ${\ensuremath{\varphi}}^{4}$ field model are topological solutions connecting its two distinct ground states. Here we establish an analogy between the excitations of a long graphene nanoribbon buckled in the transverse direction and ${\ensuremath{\varphi}}^{4}$ model results. Using molecular dynamics simulations, we investigated the dynamics of a buckled graphene nanoribbon with a single kink and with a kink-antikink pair. Several features of the ${\ensuremath{\varphi}}^{4}$ model have been observed including the kink-antikink capture at low energies, kink-antikink reflection at high energies, and a bounce resonance. Our results pave the way towards the …
Spin accumulation in metallic thin films induced by electronic impurity scattering
2021
In order to explore the spin accumulation, evaluating the spin galvanic and spin Hall effect, we utilize the semi-classical Boltzmann equation based on input from the relativistic Korringa-Kohn-Rostoker Green's function method, within the density functional theory. We calculate the spin accumulation including multiple contributions, especially skew-scattering (scattering-in term) and compare this to three different approximations, which include the isotropic and anisotropic relaxation time approximation. For heavy metals, with strong intrinsic spin-orbit coupling, we find that almost all the effects are captured within the anisotropic relaxation time approximation. On the other hand, in lig…
Berry curvature for magnetoelastic waves
2020
The Berry curvature for magnons in ferromagnetic films gives rise to new phenomena such as thermal Hall effect and a shift of a magnon wave packet at the reflection at the edge of the magnetic film. In this paper, we calculate the Berry curvature of magnetoelastic waves in ferromagnets. In order to calculate the Berry curvature, we first formulate the eigenvalue equation into a Hermitian form from the dynamical equation of motion. We find that the Berry curvature of the magnetoelastic waves shows a peak at the crossing point of the dispersions of magnons and elastic waves, and its peak value is dependent on the hybridization gap at the crossing point. In addition, the behavior of the Berry …
Modeling electron dynamics coupled to continuum states in finite volumes with absorbing boundaries
2015
arXiv:1409.1689v1
Unraveling exciton dynamics in amorphous silicon dioxide: Interpretation of the optical features from 8 to 11 eV.
2011
Physical review / B 83, 174201 (2011). doi:10.1103/PhysRevB.83.174201
Parametrization of scatterers in the Landauer-Büttiker transport theory.
1993
Electronic dc transport along a finite chain of scatterers that allow for elastic as well as inelastic processes is described within the Landauer-Buttiker approach. The transport channels in the chain are locally coupled via (current-conserving) side channels to electron reservoirs or heat baths that provide the phase randomization. Different choices for the parameters describing the inelastic coupling as well as the elastic (transmission and reflection) coefficients are compared. The scattering matrix of the chain is calculated with a recursive method. We show that the most general individual scatterer can be characterized by five parameters only, and that it can be represented by a subset…
Risken–Nummedal–Graham–Haken instability in class-B lasers
1999
We determine analytical expressions for the Risken-Nummedal-Graham-Haken multimode laser instability outside the uniform field limit in the case of very fast polarization decay (class-B laser). A new condition for the observability of that instability, concerning the value of the cavity mirrors reflectivity, is predicted.