19 research outputs found
Spin relaxation signature of colossal magnetic anisotropy in platinum atomic chains
Recent experimental data demonstrate emerging magnetic order in platinum
atomically thin nanowires. Furthermore, an unusual form of magnetic anisotropy
-- colossal magnetic anisotropy (CMA) -- was earlier predicted to exist in
atomically thin platinum nanowires. Using spin dynamics simulations based on
first-principles calculations, we here explore the spin dynamics of atomically
thin platinum wires to reveal the spin relaxation signature of colossal
magnetic anisotropy, comparing it with other types of anisotropy such as
uniaxial magnetic anisotropy (UMA). We find that the CMA alters the spin
relaxation process distinctly and, most importantly, causes a large speed-up of
the magnetic relaxation compared to uniaxial magnetic anisotropy. The magnetic
behavior of the nanowire exhibiting CMA should be possible to identify
experimentally at the nanosecond time scale for temperatures below 5 K. This
time-scale is accessible in e.g., soft x-ray free electron laser experiments.Comment: 9 pages, 3 figure
Observation of Hybrid Magnetic Skyrmion Bubbles in Fe3Sn2 Nanodisks
It is well known that there are two types of magnetic bubbles in uniaxial
magnets. Here, using Lorentz-transimission electronic microscopy magnetic
imaging, we report the direct experimental observation of 3D type-III hybrid
bubbles, which comprise N\'eel-twisted skyrmion bubbles with topological charge
Q = -1 in near-surface layers and type-II bubbles with Q = 0 in interior
layers, in Fe3Sn2 nanodisks. Using the tilted magnetic field, we further show
the controlled topological magnetic transformations of three types of bubbles
in a confined ferromagnetic nanodisk. Our observations are well reproduced
using micromagnetic simulations based on measured magnetic parameters. Our
results advance fundamental classification and understanding of magnetic
bubbles, which could propel the applications of three-dimensional magnetism.Comment: https://doi.org/10.1103/PhysRevB.107.17442
Interplay between size and stability of magnetic skyrmions
Publisher's version (útgefin grein)The relationship between the size and stability of isolated skyrmions in a magnetic monolayer is analyzed based on minimum energy path calculations and atomistic spin Hamiltonian. It is demonstrated that the energy barrier protecting the skyrmion from collapse to the ferromagnetic state is not uniquely defined by the skyrmion size, although these two properties as functions of relevant material parameters follow similar trends. Stability of nanoscale skyrmions can be enhanced by a concerted adjustment of material parameters. The proposed parameter transformation conserves the skyrmion size, but does not conserve the skyrmion shape which changes from an arrow-like pattern to a profile that resembles magnetic bubbles. This transformation of the skyrmion shape is accompanied by an increase in the collapse energy barrier and thus enhancement of skyrmion stability.This work is supported by the Russian Science Foundation (Grant No. 17-72-10195).Peer Reviewe
The skyrmion switch: turning magnetic skyrmion bubbles on and off with an electric field
Nanoscale magnetic skyrmions are considered as potential information carriers
for future spintronics memory and logic devices. Such applications will require
the control of their local creation and annihilation, which involves so far
solutions that are either energy consuming or difficult to integrate. Here we
demonstrate the control of skyrmion bubbles nucleation and annihilation using
electric field gating, an easily integrable and potentially energetically
efficient solution. We present a detailed stability diagram of the skyrmion
bubbles in a Pt/Co/oxide trilayer and show that their stability can be
controlled via an applied electric field. An analytical bubble model, with the
Dzyaloshinskii-Moriya interaction imbedded in the domain wall energy, account
for the observed electrical skyrmion switching effect. This allows us to unveil
the origin of the electrical control of skyrmions stability and to show that
both magnetic dipolar interaction and the Dzyaloshinskii-Moriya interaction
play an important role in the skyrmion bubble stabilization