Domain structure of superconducting ferromagnets

In superconducting ferromagnets the equilibrium domain structure is absent in the Meissner state, but appears in the spontaneous vortex phase (the mixed state in zero external magnetic field), though with a period, which can essentially exceed that in normal ferromagnets. Metastable domain walls are possible even in the Meissner state. The domain walls create magnetostatic fields near the sample surface, which can be used for experimental detection of domain walls.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Let

Origin and tailoring of the antiferromagnetic domain structure in α\alpha-Fe2_2O3_3 thin films unraveled by statistical analysis of dichroic spectro-microscopy (X-PEEM) images

The magnetic microstructure and domain wall distribution of antiferromagnetic $\alpha$-Fe$_2$O$_3$ epitaxial layers is determined by statistical image analyses. Using dichroic spectro-microscopy images, we demonstrate that the domain structure is statistically invariant with thickness and that the antiferromagnetic domain structure of the thin films is inherited from the ferrimagnetic precursor layer one, even after complete transformation into antiferromagnetic $\alpha$-Fe$_2$O$_3$. We show that modifying the magnetic domain structure of the precursor layer is a genuine way to tune the magnetic domain structure and domain walls of the antiferromagnetic layers

Domain Structure of Co/Pd multilayers

The observations of submicron domain structure of Co/Pd multilayers at various parts of the M-H loop and after different magnetization cycles designed to approach the global-equilibrium domain width are reported. The wall energy densities were estimated from comparison of the measured equilibrium domain width with the anhysteretic model predictions and also compared with the wall energy densities determined from the slope of major M-H loo

Nucleon structure with domain wall fermions

We report the status of RBCK calculations on nucleon structure with quenched and dynamical domain wall fermions. The quenched results for the moments of structure functions (_q), (_{\Delta u - \Delta d}), and (_{\delta q}) from 1.3 GeV cutoff lattices are complete with non perturbative renormalization (NPR). The dynamical results with two degenerate dynamical quark flavors from 1.7 GeV cutoff lattices are without NPR while the axial charge result is naturally renormalized.Comment: 3 pages, 4 figures, Lattice2004(weak

Pinning of magnetic domain walls in multiferroics

The behavior of antiferromagnetic domain wall (ADW) against the background of a periodic ferroelectric domain structure has been investigated. It has been shown that the structure and the energy of ADW change due to the interaction with a ferroelectric domain structure. The ferroelectric domain boundaries play the role of pins for magnetic spins, the spin density changes in the vicinity of ferroelectric walls. The ADW energy becomes a periodical function on a coordinate which is the position of ADW relative to the ferroelectric domain structure. It has been shown that the energy of the magnetic domain wall attains minimum values when the center of the ADW coincides with the ferroelectric wall and the periodic ferroelectric structure creates periodic coercitivity for the ADW. The neighbouring equilibrium states of the ADW are separated by a finite potential barrier.Comment: 4 pages, 2 figure

Irreversible transformation of ferromagnetic ordered stripe domains in single-shot IR pump - resonant X-ray scattering probe experiments

The evolution of a magnetic domain structure upon excitation by an intense, femtosecond Infra-Red (IR) laser pulse has been investigated using single-shot based time-resolved resonant X-ray scattering at the X-ray Free Electron laser LCLS. A well-ordered stripe domain pattern as present in a thin CoPd alloy film has been used as prototype magnetic domain structure for this study. The fluence of the IR laser pump pulse was sufficient to lead to an almost complete quenching of the magnetization within the ultrafast demagnetization process taking place within the first few hundreds of femtoseconds following the IR laser pump pulse excitation. On longer time scales this excitation gave rise to subsequent irreversible transformations of the magnetic domain structure. Under our specific experimental conditions, it took about 2 nanoseconds before the magnetization started to recover. After about 5 nanoseconds the previously ordered stripe domain structure had evolved into a disordered labyrinth domain structure. Surprisingly, we observe after about 7 nanoseconds the occurrence of a partially ordered stripe domain structure reoriented into a novel direction. It is this domain structure in which the sample's magnetization stabilizes as revealed by scattering patterns recorded long after the initial pump-probe cycle. Using micro-magnetic simulations we can explain this observation based on changes of the magnetic anisotropy going along with heat dissipation in the film.Comment: 16 pages, 6 figure

Model study for the nonequlibrium magnetic domain structure during the growth of nanostructured ultrathin films

The nonequilibrium magnetic domain structure of growing ultrathin ferromagnetic films with a realistic atomic structure is studied as a function of coverage and temperature. We apply a kinetic Monte Carlo method to a micromagnetic model describing the transition from superparamagnetic islands at low coverages to a closed ferromagnetic film. The magnetic relaxation and the island growth happen simultaneously. Near the percolation threshold a metastable magnetic domain structure is obtained with an average domain area ranging between the area of individual magnetic islands and the area of the large domains observed for thicker ferromagnetic films. We conclude that this micro-domain structure is controlled and stabilized by the nonuniform atomic nanostructure of the ultrathin film, causing a random interaction between magnetic islands with varying sizes and shapes. The average domain area and domain roughness are determined. A maximum of the domain area and a minimum of the domain roughness are obtained as a function of the temperature.Comment: 19 pages, 4 Postscript figures; to be published in J. Magn. Magn. Mater., accepted (2001); completely revised manuscrip

Statistical theory of the excited strip domain structure

A statistical theory of the strip domain structure excited in a bubble film by an oscillating magnetic field is developed. The theory is based on the consideration of the strip domain structure as a thermodynamic system characterized by the spectrum of domain walls oscillation and an effective temperature that is caused by an oscillating magnetic field and film nonuniformities. We found the thermodynamic characteristics of that domain structure and calculated its period as a function of the frequency and amplitude of an oscillating magnetic field.Comment: 6 pages, 3 figure

Nucleon structure functions with domain wall fermions

We present a quenched lattice QCD calculation of the first few moments of the polarized and un-polarized structure functions of the nucleon. Our calculations are done using domain wall fermions and the DBW2 gauge action with inverse lattice spacing ~1.3GeV, physical volume approximatelly (2.4 fm)^3, and light quark masses down to about 1/4 the strange quark mass. Values of the individual moments are found to be significantly larger than experiment, as in past lattice calculations, but interestingly the chiral symmetry of domain wall fermions allows for a precise determination of the ratio of the flavor non-singlet momentum fraction to the helicity distribution, which is in very good agreement with experiment. We discuss the implications of this result. Next, we show that the chiral symmetry of domain wall fermions is useful in eliminating mixing of power divergent lower dimensional operators with twist-3 operators. Finally, we find the isovector tensor charge at renormalization scale 2 GeV in the MS bar scheme to be 1.192(30), where the error is the statistical error only.Comment: 41 pages, 17 figure