arXiv subjects

Daria Gusakova

Publications and source records attributed to Daria Gusakova.

7 recordsLinked to original sources

arXiv2026

Non-reciprocity and exchange-spring delay of domain-wall Walker breakdown in magnetic nanowires with azimuthal magnetization

Domain-wall (DW) motion is a crucial process involved in magnetization reversal, be it under magnetic field or spin-polarized current stimulus. In most cases the DW speed does not exceed $\approx$100m/s and collapses above a given threshold of the stimulus, an effect known as Walker breakdown. A few specific material properties have been identified to delay the breakdown of speed by increasing the energy barrier preventing internal precession. We show that in a 3D nanomagnetic system, here with vortex-state domains, the topology of the magnetization distribution may intrinsically and robustly delay the Walker breakdown due to an exchange-spring effect. However, in contrast to situations in lower dimension, the motion remains steady-state. In addition, curvature induces a major non-reciprocal effect, delaying or not the Walker breakdown depending on the sequence of chiralities of the azimuthal domains on both sides of the DW, independent of its direction of motion.

cond-mat.mes-hall↗

arXiv2025

Simulation of current-driven magnetisation switching in nanopillars with Perpendicular Shape Anisotropy

The Perpendicular Shape Anisotropy Spin Transfer Torque Magnetic Random Access Memory (PSA-STT-MRAM) is a recent concept proposed to maintain the thermal stability of standard MRAM at small diameters, considering thick vertical pillars as the free layer. In order to explore the specific physics of PSA-STT-MRAMs expected in relation with their three-dimensional nature, we have performed simulations combining a micromagnetic model coupled self-consistently with spin-dependent transport equations. The 3D shape induces flower states at the upper and lower surfaces. Besides, the field-like component of STT is found to be larger than in standard MRAMs, suggesting that it needs to be considered. The combination of both effects leads to the excitation of high-order 3D ferromagnetic resonance modes, playing a key role in magnetisation reversal. These results highlight features of 3D nanomagnetic systems, largely disregarded so far, which need to be considered to optimise PSA-STT-MRAM to be a competitive solution for technological implementation.

cond-mat.mes-hall↗

arXiv2025

Imprinting of skyrmions and bimerons in an antiferromagnet

Topologically protected magnetic states in condensed matter physics, particularly antiferromagnetic (AFM) skyrmions (Sks) and bimerons (Bms), offer promising prospects for terahertz dynamics and sustained current-induced motion, thanks to their compensating multiple sub-lattice structure. However, nucleating AFM Sks and Bms is challenging due to the lack of net magnetization. Previous attempts to imprint pre-defined Sks and Bms in a ferromagnet (FM) and transfer them to an AFM using interfacial exchange bias in FM/AFM heterostructures have been hindered by complex multilayers with discontinuities, polycrystallinity, or multipartite chiral AFMs. Employing atomistic spin simulations, we demonstrate the viability of texture imprinting for nucleating Sks and Bms in AFMs, using a prototypical bipartite AFM layer in a multilayer structure free from discontinuities. Such imprinting is a crucial step towards understanding the static and dynamic properties of natural antiferromagnetic textures and their unique properties.

cond-mat.mtrl-sci↗

arXiv2023

Local setting of spin textures in a granular antiferromagnet

Controlling the magnetic order of antiferromagnets is challenging due to their vanishing net magnetization. For this reason, the study of local spin textures in antiferromagnets is restricted by the difficulty in nucleating such states. Here, using atomistic simulations we demonstrate a method for nucleating localized spin textures in the grains of thin film antiferromagnet, $γ$-IrMn$_3$. Utilising the exchange bias coupling between a ferromagnet and an antiferromagnet, we set the spin texture in the latter from a predefined spin texture in the former by means of a thermal cycling procedure. The local textures set in the antiferromagnetic grains are shown to be stable against field perturbations. We also discuss how various material parameters affect the efficiency of the setting and the characteristics of these set textures. The setting of antiferromagnetic spin textures provides a potential route to antiferromagnetic spintronic devices with non-collinear spin states such as skyrmions, bubbles and domain walls.

cond-mat.mes-hall↗

arXiv2020

Theoretical study of current-induced domain wall motion in magnetic nanotubes with azimuthal domains, including Œrsted field and spin-transfer torques

We report a theoretical overview of the magnetic domain wall behavior under an electric current in infinitely-long nanotubes with azimuthal magnetization, combining the $1$D analytic model and micromagnetic simulations. We highlight effects that, besides spin-transfer torques already largely understood in flat strips, arise specifically in the tubular geometry: the \OErsted field and curvature-induced magnetic anisotropy resulting both from exchange and material growth. Depending on both the geometry of the tube and the strength of the azimuthal anisotropy, Bloch or Néel walls arise at rest, resulting in two regimes of motion largely dominated by either spin-transfer torques or the \OErsted field. We determine the Walker breakdown current in all cases, and highlight the most suitable parameters to achieve high domain wall speed.

cond-mat.mes-hall↗

arXiv2020

Measurement of the Spin Absorption Anisotropy in Lateral Spin Valves

The spin absorption process in a ferromagnetic material depends on the spin orientation relativelyto the magnetization. Using a ferromagnet to absorb the pure spin current created within a lateralspin-valve, we evidence and quantify a sizeable orientation dependence of the spin absorption inCo, CoFe and NiFe. These experiments allow determining the spin-mixing conductance, an elusivebut fundamental parameter of the spin-dependent transport. We show that the obtained valuescannot be understood within a model considering only the Larmor, transverse decoherence and spindiffusion lengths, and rather suggest that the spin-mixing conductance is actually limited by theSharvin conductance.

cond-mat.mtrl-sci↗

arXiv2009

Proximity effect in atomic-scaled hybrid superconductor/ferromagnet structures: crucial role of electron spectra

We study the influence of the configuration of the majority and minority spin subbands of electron spectra on the properties of atomic-scaled superconductor-ferromagnet S-F-S and F-S-F hybrid structures. At low temperatures, the S/F/S junction is either a 0 or junction depending on the energy shift between S and F materials and the anisotropy of the Fermi surfaces. We found that the spin switch effect in F/S/F system can be reversed if the minority spin electron spectra in F metal is of the hole-like type.

cond-mat.supr-con↗