Micromagnetics of the Domain Wall Mobility in Permalloy Nanowires

The domain wall mobility in long permalloy nanowires with thicknesses of 2-20 nm and widths of 50-200 nm has been simulated. The domain wall is driven into motion by an external magnetic field and the average wall mobility is calculated after the wall has traveled 2.5 mum along the wire. The results were obtained using the three-dimensional dynamic Landau-Lifshitz equation. We find that the domain wall mobility decreases linearly up to the critical field called the Walker field. The decreasing wall mobility is related to the decrease in the dynamic domain wall length as the applied field is increased. The value of the critical field is dependent on the thickness and width of the wire. At the critical field the mobility decreases by an order of magnitude. Above the Walker field the average mobility remains relatively constant for all driving fields, while the instantaneous mobility shows regions of high mobility with long periods of almost no mobility. For large applied fields the domain wall velocity can be large even though the average mobility is low

Simulating the Maximum Domain Wall Speed in a Magnetic Nanowire

The dynamics of domain wall motion in permalloy nanowires have been simulated utilizing the Landau-Lifshitz-Gilbert (LLG) equation of motion. The simulation results are presented in terms of the domain wall speed for ranges of the Gilbert damping parameter alpha and nanowire width. The maximum domain wall speed is independent of alpha. The speed of the domain wall can be increased by increasing the nanowire width, but this lowers the critical field. For applied fields below the critical field, the wall moves uniformly along the wire and the speed of the wall increases with increases in the driving field. This behavior is consistent with current analytic models; however, the models overestimate both the value of the domain wall speed and the critical field

Black Holes in Higher Dimensions (Black Strings and Black Rings)

The main focus of this session was the presentation of new higher-dimensional black hole solutions, including black rings, black strings, and multi black holes, and the study of their properties. Besides new asymptotically flat and locally asymptotically flat black objects also new black holes with anti-de Sitter asymptotics were reported. The studies of their properties included the investigation of their stability, their thermodynamics, their analyticity and their existence. Furthermore, the geodesics in such higher-dimensional space-times were investigated.Comment: Summary of session BH1 at MG13 in Stockholm, 14 page

Simulated Domain Wall Dynamics in Magnetic Nanowires

The simulated domain wall dynamics in rectangular 10 nm thick, 2000 nm long Permalloy wires of varying width is presented. In the absence of an applied field the static domain wall length is found to be linearly dependent to the width of the nanowire. As magnetic fields of increasing strength are applied along the wire’s long axis, the domain wall motion changes from a uniform reversal to a steplike reversal. The onset of the stepping motion leads to a decrease in the domain wall speed. By continuing to increase the field it is possible to decrease the time between steps increasing the domain wall speed. The critical field associated with the crossover from uniform to nonuniform reversal decreases as the wire width increases

Field Induced Domain Wall Collisions in Thin Magnetic Nanowires

In a two-dimensional magnetic nanowire, it is possible to engineer collisions between two domain walls put into motion by an externally applied field. We show that the topological defects that define the domain wall can be controlled to allow for both domain wall annihilation and preservation during the collisions as long as the wire remains thin. The preservation process can be used to release pinned domain walls from notches with small applied fields

Do we measure what we get?

Performance measures shall enhance the performance of companies by directing the attention of decision makers towards the achievement of organizational goals. Therefore, goal congruence is regarded in literature as a major factor in the quality of such measures. As reality is affected by many variables, in practice one has tried to achieve a high degree of goal congruence by incorporating an increasing number of these variables into performance measures. However, a goal congruent measure does not lead automatically to superior decisions, because decision makers’ restricted cognitive abilities can counteract the intended effects. This paper addresses the interplay between goal congruence and complexity of performance measures considering cognitively-restricted decision makers. Two types of decision quality are derived which allow a differentiated view on the influence of this interplay on decision quality and learning. The simulation experiments based on this differentiation provide results which allow a critical reflection on costs and benefits of goal congruence and the assumptions regarding the goal congruence of incentive systems

Development of "Blossom-Protect" - a yeast preparation for the reduction of blossom infections by fire blight

In organic apple-growing control agents are necessary to prevent the blossoms being infected by the fire blight pathogen Erwinia amylovora. Detached apple blossoms were used as an experimental model to develop preparations based on yeast isolates for use in the control of fire blight. Several yeast isolates reduced disease incidence in apple blossoms. The efficiency of yeast isolates was increased by developing a suitable formulation. This yeast preparation exhibited high efficiency in the control of fire blight in field-trials and will be marketed under the tradename "Blossom- Protect"