Search results for "TEXTURE"

Near-coincidence lattice method for the determination of epitaxy strains during oxidation of metals

2000

Abstract A theoretical method is proposed to evaluate the strains due to epitaxy between a metal and its oxide. Based on Bollmann’s approach of two adjoining grains, it uses the quantitative texture analysis of the two materials separated by the phase boundary. Our study of the Zr/ZrO 2 and Mo/MoO 3 systems reveals strong correlations between the criterion of best fit proposed by Bollmann and the orientation distribution function obtained by a quantitative texture analysis. The results of this study are used in a thermo-mechano-chemical simulation of the oxidation process of zirconium, which leads to this observation: two different zirconia orientations induce two different oxidation kineti…

Nonlinear Dynamics of Topological Ferromagnetic Textures for Frequency Multiplication

2020

We propose that the non-linear radio-frequency dynamics and nanoscale size of topological magnetic structures associated to their well-defined internal modes advocate for their use as in-materio scalable frequency multipliers for spintronic systems. Frequency multipliers allow for frequency conversion between input and output frequencies, and thereby significantly increase the range of controllably accessible frequencies. In particular, we explore the excitation of eigenmodes of topological magnetic textures by fractions of the corresponding eigenfrequencies. We show via micromagnetic simulations that low-frequency perturbations to the system can efficiently excite bounded modes with a high…

Enhanced Nonadiabaticity in Vortex Cores due to the Emergent Hall Effect.

2016

We present a combined theoretical and experimental study, investigating the origin of the enhanced non-adiabaticity of magnetic vortex cores. Scanning transmission X-ray microscopy is used to image the vortex core gyration dynamically to measure the non-adiabaticity with high precision, including a high confidence upper bound. Using both numerical computations and analytical derivations, we show that the large non-adiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture-induced emergent Hall effect. This enhanced non-adiabaticity is only present in two- and three-dimensional magnetic textures such as vortices and skyrmions…

Chiral Hall Effect in Noncollinear Magnets from a Cyclic Cohomology Approach

2020

We demonstrate the emergence of an anomalous Hall effect in chiral magnetic textures which is neither proportional to the net magnetization nor to the well-known emergent magnetic field that is responsible for the topological Hall effect. Instead, it appears already at linear order in the gradients of the magnetization texture and exists for one-dimensional magnetic textures such as domain walls and spin spirals. It receives a natural interpretation in the language of Alain Connes' noncommutative geometry. We show that this chiral Hall effect resembles the familiar topological Hall effect in essential properties while its phenomenology is distinctly different. Our findings make the reinterp…

2017

Topological magnetic textures - like skyrmions - have become a major player in the design of next-generation magnetic storage technology due to their stability and the control of their motion by ultra-low current densities. A major challenge to develop this new skyrmion-based technology is to achieve the controlled and deterministic creation of magnetic skyrmions without the need of complex setups. We demonstrate a solution to this challenge by showing how to create skyrmions and other magnetic textures in ferromagnetic thin films by means of a homogeneous DC current and without requiring Dzyaloshinskii-Moriya interactions. This is possible by exploiting a static loss of stability arising f…

Spin texture of time-reversal symmetry invariant surface states on W(110)

2016

AbstractWe find in the case of W(110) previously overlooked anomalous surface states having their spin locked at right angle to their momentum using spin-resolved momentum microscopy. In addition to the well known Dirac-like surface state with Rashba spin texture near the "Equation missing"-point, we observe a tilted Dirac cone with circularly shaped cross section and a Dirac crossing at 0.28 × "Equation missing" "Equation missing" within the projected bulk band gap of tungsten. This state has eye-catching similarities to the spin-locked surface state of a topological insulator. The experiments are fortified by a one-step photoemission calculation in its density-matrix formulation.

The reactor mixing angle and CP violation with two texture zeros in the light of T2K

2012

We reconsider the phenomenological implications of two texture zeros in symmetric neutrino mass matrices in the light of the recent T2K result for the reactor angle and the new global analysis which gives also best fit values for the Dirac CP phase delta. The most important results of the analysis are: Among the viable cases classified by Frampton et al. only A1 and A2 predict the reactor mixing angle to be different from zero at 3 sigma. Furthermore these two cases are compatible only with a normal mass spectrum in the allowed region for the reactor angle. At the best fit value A1 and A2 predict 0.024 >= sin^2(theta13) >= 0.012 and 0.014 <= sin^2(theta13) <= 0.032, respectively…

Fritzsch neutrino mass matrix fromS3symmetry

2010

We present an extension of the Standard Model (SM) based on the discrete flavor symmetry S3 which gives a neutrino mass matrix with two-zero texture of Fritzsch-type and nearly diagonal charged lepton mass matrix. The model is compatible with the normal hierarchy only and predicts the sine squared of the reactor angle to be 0.01 at the best fit values of solar and atmospheric parameters and maximal leptonic CP violation.

Bilarge neutrino mixing and Abelian flavor symmetry

2012

We explore two bilarge neutrino mixing Anzatze within the context of Abelian flavor symmetry theories: (BL1) sin theta(12) similar to lambda, sin theta(13) similar to lambda, sin theta(23) similar to lambda, and (BL2) sin theta(12) similar to lambda, sin theta(13) similar to lambda, sin theta(23) similar to 1 - lambda. The first pattern is proposed by two of us and is favored if the atmospheric mixing angle theta(23) lies in the first octant, while the second one is preferred for the second octant of theta(23). In order to reproduce the second texture, we find that the flavor symmetry should be U(1) x Z(m), while for the first pattern the flavor symmetry should be extended to U(1) x Z(m) x …

Novel stripe textures in nonchiral hexatic liquid-crystal films

1992

A novel macroscopic stripe texture has been observed in freely suspended films of nonchiral liquid crystal, uniform stripes of alternating molecular orientation form spontaneously at the smectic-C--to--surface-hexatic phase transition and broaden with decreasing temperature. The stripes are identified as splay domains whose formation is attributed to the polar symmetry of the hexatic surface layers. Transverse (director bend) walls, which lead to an additional modulation of the basic one-dimensional pattern, are manifested inside thick circular islands as twelve-armed star defects.