"Domain Walls" in Magnetic Superconductors

Paper by H. Suh

Kondo Temperature in Multilevel Quantum Dots

We develop a general method to evaluate the Kondo temperature in a multilevel quantum dot that is weakly coupled to conducting leads. Our theory reveals that the Kondo temperature is strongly enhanced when the intradot energy-level spacing is comparable to or smaller than the charging energy. We propose an experiment to test our result, which consists of measuring the size-dependence of the Kondo temperature.Comment: 4 pages, 1 figure and supplementary material. Revised and improved version, to appear in Phys. Rev. Let

Increasing Stability of Crew Schedules in Airlines

In airline traffic disruptions occur frequently and cannot be totally avoided. They may lead to infeasible aircraft and crew schedules during the day of operations, due to absence of resources or violation of crew rules. The process of finding new schedules in such cases is called recovery or disruption management. The short-term recovery actions usually imply additional costs meaning that the total operational costs of a crew schedule can be significantly higher than the original planned costs. It is generally desirable to construct the schedule already in the planning phase in such a way that not just the planned costs, but the total operational costs are minimized. The goal is thus to construct schedules which remain feasible or can be recovered without high costs in cases of disturbances. This approach is generally called robust scheduling

Magnetization reversal and nonexponential relaxation via instabilities of internal spin waves in nanomagnets

A magnetic particle with atomic spins ordered in an unstable direction is an example of a false vacuum that decays via excitation of internal spin waves. Coupled evolution of the particle's magnetization (or the vacuum state) and spin waves, considered in the time-dependent vacuum frame, leads to a peculiar relaxation that is very fast at the beginning but slows down to a nonexponential long tail at the end. The two main scenarios are linear and exponential spin-wave instabilities. For the former, the longitudinal and transverse relaxation rates have been obtained analytically. Numerical simulations show that the particle's magnetization strongly decreases in the middle of reversal and then recovers.Comment: 6 EPL pages, 4 figure

Evidence for spin-flip scattering and local moments in dilute fluorinated graphene

The issue of whether local magnetic moments can be formed by introducing adatoms into graphene is of intense research interest because it opens the window to fundamental studies of magnetism in graphene, as well as of its potential spintronics applications. To investigate this question we measure, by exploiting the well-established weak localization physics, the phase coherence length L_phi in dilute fluorinated graphene. L_phi reveals an unusual saturation below ~ 10 K, which cannot be explained by non-magnetic origins. The corresponding phase breaking rate increases with decreasing carrier density and increases with increasing fluorine density. These results provide strong evidence for spin-flip scattering and points to the existence of adatom-induced local magnetic moment in fluorinated graphene. Our results will stimulate further investigations of magnetism and spintronics applications in adatom-engineered graphene.Comment: 9 pages, 4 figures, and supplementary materials; Phys. Rev. Lett. in pres

Crossover from thermal to quantum creep in layered antiferromagnetic superconductor

The influence of the antiferromagnetic order on the superconductor in the mixed state results in creation of spin-flop domains along the cores of the vortex lines. It is shown that this phenomenon makes possible crossover from quantum creep regime to thermal one, and vice versa, at constant temperature. To do this one needs to simply change the intensity or the direction of applied magnetic field in the basal ${\bf ab}$ plane of layered structure.Comment: 9 pages, Latex(elsart.cls), 2 figures. to be published in Physica C vol 340 nr 2/

Quantum Dynamics of a Nanomagnet driven by Spin-Polarized Current

A quantum theory of magnetization dynamics of a nanomagnet as a sequence of scatterings of each electron spin with the macrospin state of the magnetization results in each encounter a probability distribution of the magnetization recoil state associated with each outgoing state of the electron. The quantum trajectory of the magnetization contains the average motion tending in the large spin limit to the semi-classical results of spin transfer torque and the fluctuations giving rise to a quantum magnetization noise and an additional noise traceable to the current noise.Comment: 4 pages, 4 figure