A5035677184- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Magneto-Optical Properties and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Advanced Memory and Neural Computing
- Theoretical and Computational Physics
- Neural Networks and Reservoir Computing
- Multiferroics and related materials
- Advanced Electron Microscopy Techniques and Applications
- Heusler alloys: electronic and magnetic properties
- Geomagnetism and Paleomagnetism Studies
- Molecular Junctions and Nanostructures
- ZnO doping and properties
- Metamaterials and Metasurfaces Applications
- Magnetic Field Sensors Techniques
- Advanced Materials and Mechanics
- Wireless Sensor Networks for Data Analysis
- Numerical methods for differential equations
- Electromagnetic Simulation and Numerical Methods
- Semiconductor Quantum Structures and Devices
- Mechanical and Optical Resonators
- Nonlinear Dynamics and Pattern Formation
- Quantum Computing Algorithms and Architecture
University of Gothenburg
2015-2022
Nanosc (Sweden)
2018-2022
University of Exeter
2011-2018
KTH Royal Institute of Technology
2016-2018
Ghent University
2013-2015
Vasyl' Stus Donetsk National University
2012
We report on the design, verification and performance of MuMax3, an open-source GPU-accelerated micromagnetic simulation program. This software solves time- space dependent magnetization evolution in nano- to micro scale magnets using a finite-difference discretization. Its high low memory requirements allow for large-scale simulations be performed limited time inexpensive hardware. verified each part by comparing results analytical values where available standard problems. MuMax3 also...
In the last twenty years, numerical modeling has become an indispensable part of magnetism research.It a standard tool for both exploration new systems and interpretation experimental data.In five capabilities micromagnetic have dramatically increased due to deployment graphical processing units (GPU), which sped up calculations factor 200.This enabled many studies were previously unfeasible.In this topical review, we give overview approach show how it contributed forefront current research.
We use time resolved scanning Kerr microscopy and analytical numerical calculations to demonstrate coupling of uniform global microwave field propagating spin waves for emerging magnonic architectures. The is mediated by the local dynamic dipolar produced magnetization a resonantly driven all-metallic magnetic microwave-to-spin-wave transducer. can exceed that incident one order magnitude. Our simulations ability transducer unidirectionally emit coherent exchange nanoscale wavelengths with...
Spin torque and spin Hall effect nano-oscillators generate high intensity wave auto-oscillations on the nanoscale enabling novel microwave applications in spintronics, magnonics, neuromorphic computing. For their operation, these devices require externally generated currents either from an additional ferromagnetic layer or a material with angle. Here we demonstrate highly coherent field current tunable signals nano-constrictions single 15-20 nm thick permalloy layers oxide interfaces. Using...
Ising machines (IMs) are physical systems designed to find solutions combinatorial optimization (CO) problems mapped onto the IM via coupling strengths between its binary spins. Using intrinsic dynamics and different annealing schemes, relaxes over time lowest-energy state, which is solution CO problem. IMs have been implemented on platforms, interacting nonlinear oscillators particularly promising candidates. Here we demonstrate a pathway towards an oscillator-based using arrays of...
We have used micromagnetic simulations to demonstrate a method for controlling the amplitude and phase of spin waves propagating inside magnonic waveguide. The employs nanomagnet formed on top function proposed device is controlled by defining static magnetization direction nanomagnet. result valve or shifter waves, acting as carrier information computation data processing within emerging wave logic architectures magnonics. concept offers such technically important benefits energy...
An all-optical experiment long utilized to image phonons excited by ultrashort optical pulses has been applied a magnetic sample. In addition circular ripples due surface acoustic waves, we observe an X-shaped pattern formed propagating spin waves. The emission of waves from the pulse epicenter in form collimated beams is qualitatively reproduced micromagnetic simulations. We explain observed terms group velocity distribution Damon-Eshbach magnetostatic reciprocal space and wave vector...
We use micromagnetic simulations to map out and compare, the linear auto-oscillating modes in constriction-based spin Hall nano-oscillators as a function of applied magnetic field with varying magnitude out-of-plane angle. demonstrate that for all possible configurations auto-oscillations emerge from localized constriction. For directions tending towards plane, these are so-called "edge" type, i.e. at opposite sides When magnetization direction instead approaches film normal, transform...
We demonstrate highly efficient spin Hall nano-oscillators (SHNOs) based on NiFe/β-W bilayers. Thanks to the very high angle of β-W, we achieve more than a 60% reduction in auto-oscillation threshold current compared NiFe/Pt The structural, electrical, and magnetic properties bilayers, as well microwave signal generation SHNOs, have been studied detail. Our results provide promising path for realization low-current SHNO devices with spin-orbit torque from β-W.
Abstract Spin Hall nano-oscillators (SHNOs) are emerging spintronic devices for microwave signal generation and oscillator-based neuromorphic computing combining nano-scale footprint, fast ultra-wide frequency tunability, CMOS compatibility, strong non-linear properties providing robust large-scale mutual synchronization in chains two-dimensional arrays. While SHNOs can be tuned via magnetic fields the drive current, neither approach is conducive to individual SHNO control large Here, we...
We report a continuous medium theory of dispersion and scattering spin waves propagating in thin nanowire magnonic waveguides with curved regions. Assuming that the static magnetization is aligned along waveguide, curvature leads to “geometrical” effective magnetic field term proportional square ratio exchange length radius waveguide. The small enough favor use bended planar data architectures. However, stronger (multiple) winding (e.g., within helical structures) could enable design desired...
Short wavelength exchange-dominated propagating spin waves will enable magnonic devices to operate at higher frequencies and data transmission rates. While giant magnetoresistance (GMR)-based magnetic nanocontacts are efficient injectors of waves, the generated wavelengths 2.6 times nano-contact diameter, electrical signal strength remains too weak for applications. Here we demonstrate nano-contact-based wave generation in tunnel junctions observe large-frequency steps consistent with...
Propagating spin waves generated by a metal-based Hall nano-oscillator for highly energy-efficient wave technology.
Thermal fluctuations play an increasingly important role in micromagnetic research relevant for various biomedical and other technological applications. Until now, it was deemed necessary to use a time stepping algorithm with fixed step order perform simulations at nonzero temperatures. However, Berkov Gorn have shown that the drift term which generally appears when solving stochastic differential equations can only influence length of magnetization. This quantity is however case...
A phenomenological equation called Landau-Lifshitz-Baryakhtar (LLBar) equation, which could be viewed as the combination of Landau-Lifshitz (LL) and an extra "exchange damping" term, was derived by Baryakhtar using Onsager's relations. We interpret origin this nonlocal damping linking it to spin current pumping. The LLBar is investigated numerically analytically for wave decay domain wall motion. Our results show that lifetime propagation length short-wavelength magnons in presence much...
We report upon a theoretical study of collective magnonic modes in pairs magnetic nano-elements with quasi-uniform magnetization. The mode spectrum and character are numerically computed for an individual isolated nano-element then used to analytically calculate the splitting due inter-element magneto-dipole interaction. results compared those obtained using direct simulations elements, yielding generally good agreement. For edge interaction between edges neighboring elements can exceed that...
We report a numerical implementation of the Landau-Lifshitz-Baryakhtar theory that dictates micromagnetic relaxation term obeys symmetry magnetic crystal, i.e., replacing single intrinsic damping constant with tensor corresponding symmetry. The effect anisotropic is studied in thin saturated ferromagnetic disk and an ellipse without uniaxial magnetocrystalline anisotropy. investigate angular dependence linewidth magnonic resonances respect to given structure tensor. simulations suggest...
Magnetic droplets are nontopological dynamical solitons that can be nucleated in nanocontact based spin torque nano-oscillators (STNOs) with perpendicular magnetic anisotropy free layers. While theory predicts the droplet should of same size as nanocontact, its inherent drift instability has thwarted attempts at observing it directly using microscopy techniques. Here, we demonstrate highly stable all-perpendicular STNOs and present first detailed images scanning transmission X-ray...
We experimentally study the auto-oscillating spin-wave modes in NiFe/$\beta-$W constriction-based spin Hall nano-oscillators as a function of bias current, in-plane applied field strength, and azimuthal angle, low-field range 40-80 mT. observe two different modes: i) linear-like mode confined to minima internal near edges nanoconstriction, with weak frequency dependencies on current ii) second, lower that has significantly higher threshold stronger both external angle. Our micromagnetic...
Designers of nano-scale magnonic devices would benefit from methods their evaluation that do not require one to access the microscopic level description or construct device prototypes. Here, we propose a numerical micromagnetics version such method, in which are considered as two-port linear networks and can therefore be described terms s-parameters (i.e., reflection transmission characteristics). In micromagnetic model, sample is composed device-under-test situated between input output...
We present a method of calculation the effective magnetic permeability magnonic metamaterials containing arrays inclusions arbitrary shapes. The fully takes into account spectrum spin waves confined in inclusions. evaluate by considering particular case metamaterial formed stack identical two-dimensional (2D) periodic hexagonal disk-shaped nonmagnetic matrix. Two versions are considered. first approach is based on simple semianalytical theory that uses numerically calculated susceptibility...