arXiv subjects

Sebastián Allende

Publications and source records attributed to Sebastián Allende.

3 recordsLinked to original sources

arXiv2026

Magnetic texture modulated superconductivity in superconductor/ferromagnet shells of semiconductor nanowires

In a one-dimensional ferromagnet-superconductor nanowire, magnetism can suppress superconductivity except where the Zeeman field is suppressed, for example domain wall superconductivity (DWS) near magnetic domain walls or multi-domain-averaged superconductivity (MDAS) in multi-domain states where the net magnetization over the coherence length averages to nearly zero. Here we study full-shell InAs/EuS/Al nanowires using scanning SQUID magnetometry and transport, and find superconductivity in the Al shell only when the EuS is in a multi-domain state, consistent with both DWS and MDAS, and absent in the saturated single-domain state. Scanning SQUID magnetometry further shows that the EuS magnetic texture is position dependent and reconfigurable by small changes in external magnetic field, including moving a well-defined domain wall at $\approx$5.5 $μ$m/mT with sub-mT fields, implying that any associated localized superconducting region would likewise be movable. Such magnetic texture controlled superconductivity along a nanowire may be useful for topological qubits, Andreev spin qubits, superconducting logic, and memory devices.

cond-mat.mes-hall↗

arXiv2025

Elastic Dislocation-based Skyrmion Traps: Fundamentals and Applications

Topologically secure spin configurations, such as skyrmions and bimerons, offer a compelling alternative to conventional magnetic domains, potentially enabling high-density, low-power spintronic devices. These pseudo-particles, characterized by their swirling spin textures and nontrivial topological charges, are prevalent and notably influence their electronic, magnetic, and mechanical traits. This paper provides an in-depth overview of the interaction between a screw dislocation within a distorted magnetic lattice, exploring possible coupling mechanisms and establishing a promising link between two disparate topics in materials science: topological magnetism and topological elasticity. We first provide a classical analysis of skyrmion motion that reveals the dislocations as shallow traps on the magnetic texture. Afterwards, we provide an analysis of the quantized motion of the skyrmion and identify its quantum states. We conclude by illustrating how the ideas in our paper can be implemented in simple yet compelling devices based on the shallow traps from an array of dislocations acting as frets in a race-track, controlling the motion with a low current activation mechanism.

cond-mat.mes-hall↗

arXiv2024

Bimerons as Edge states in Thin Magnetic Strips

Magnetic bimerons are potential information carriers in spintronic devices. Bimerons, topologically equivalent to skyrmions, manifest in chiral magnetic systems with in-plane magnetization due to anisotropies or external magnetic fields. Applications demanding their current-driven motion face significant challenges, notably the bimeron Hall effect, which causes transverse movement and annihilation at nanomagnet borders. This study addresses the problem of stabilizing bimeron propagation under current-driven conditions. We demonstrate that bimerons can propagate through thin ferromagnetic strips without annihilation when the easy-axis anisotropy and the electric current are orthogonal. Our findings indicate that below a threshold value of current, the repulsion between the bimeron and the strip boundary allows for stable soliton propagation, even in bent regions. This phenomenon extends to bimeron chains, which propagate parallel to the current flow. By enabling stable long-distance propagation, our results open new avenues for developing bimeron-based racetrack memory devices, enhancing the efficiency and reliability of future spintronic applications.

cond-mat.mes-hall↗