Controllable chiral Majorana modes by noncollinear magnetic configuration in a topological Josephson junction

Recently, theory and experiment both have confirmed a Majorana zero mode to induce selective equal spin Andreev reflection (SESAR). Herein, we theoretically present controllable chiral Majorana modes (CMMs) by noncollinear magnetic configuration in a Josephson junction on a topological insulator with two ferromagnetic insulators (FIs) sandwiched in between two superconductors (SCs). It is shown that an additional phase shift is induced by the different chirality of the CMMs at the two FI/SC interfaces, whose magnitude is determined by misorientational angle θ, which can be administrated by the Andreev bound surface energies. The angle θ is found to result in the 0-π state transition and Φ0 supercurrent. Particularly, due to the SESAR, the coexistence of fully spin-polarized spin-singlet and -triplet correlations is exhibited with the exclusive fully spin-polarized spin-triplet (singlet) correlation corresponding to the ferromagnetic (F) [antiferromagnetic (AF)] configuration. For the two magnetizations only along y-axis, there exist no additional phase shift and topological supercurrent with fully spin-polarized correlations, especially, the supercurrent in the AF configuration is a lot larger than that in the F one, which is strongly dependent on the exchange field strength and FI length, thus even leading to 100% supercurrent magnetoresistance. The results can be employed to not only identify the topological SCs but also design a perfect topological supercurrent spin valve device.

Magnetic configuration scans during divertor operation of Wendelstein 7-X

Wendelstein 7-X (Greifswald, Germany) is an advanced stellarator, which uses the modular coil concept to realize a magnetic configuration optimized for fusion-relevant plasma properties. The magnet system of the machine allows a variation of the rotational transform (iota) at the boundary. In the latest Wendelstein 7-X operational phase a dedicated configuration scan has been performed varying the rotational transform between magnetic configurations with iota=5/4 and iota=5/5 at the boundary. This paper presents an overview of the experiments and of the main results with respect to confinement and stability. The main observation is an increase of the plasma energy in several intermediate configurations of the scan when the 5/5-islands are close to the plasma boundary but still inside the last-closed-flux-surface. In addition, these configurations showed marked MHD-activity with a crashing behavior related to the 5/5-islands. The corresponding mode amplitude was correlated with the size of the internal 5/5 islands.

Scaling Up the Production of Electrodeposited Nanowires: A Roadmap towards Applications

The use of metallic nanowires is mostly reduced to scientific areas where a small quantity of nanostructures are needed. In order to broaden the applicability of these nanomaterials, it is necessary to establish novel synthesis protocols that provide a larger amount of nanowires than the conventional laboratory fabrication processes at a more competitive cost. In this work, we propose several modifications to the conventional electrochemical synthesis of nanowires in order to increase the production with considerably reduced production time and cost. To that end, we use a soft anodization procedure of recycled aluminum at room temperature to produce the alumina templates, followed by galvanostatic growth of CoFe nanowires. We studied their morphology, composition and magnetic configuration, and found that their properties are very similar to those obtained by conventional methods.