22 research outputs found
Exploring the origins of the Dzyalloshinski-Moria interaction in MnSi
By using magnetization and small-angle neutron scattering (SANS)
measurements, we have investigated the magnetic behavior of Mn_{1-x}Ir_{x}Si
system to explore the effect of increased carrier density and spin-orbit
interaction on the magnetic properties of MnSi. We determine estimates of the
spin wave stiffness and the Dzyalloshinski-Moria, DM, interaction strength and
compare with Mn_{1-x}Co_{x}Si and Mn_{1-x}Fe_{x}Si. Despite the large
differences in atomic mass and size of the substituted elements,
Mn_{1-x}Co_{x}Si and Mn_{1-x}Ir_{x}Si show nearly identical variations in their
magnetic properties with substitution. We find a systematic dependence of the
transition temperature, the ordered moment, the helix period and the DM
interaction strength with electron count for Mn{1-x}Ir{x}Si, Mn_{1-x}Co_{x}Si,
and Mn_{1-x}Fe_{x}Si indicating that the magnetic behavior is primarily
dependent upon the additional carrier density rather than on the mass or size
of the substituting species. This indicates that the variation in magnetic
properties, including the DM interaction strength, are primarily controlled by
the electronic structure as Co and Ir are isovalent. Our work suggests that
although the rigid band model of electronic structure along with Moira's model
of weak itinerant magnetism describe this system surprisingly well,
phenomenological models for the DM interaction strength are not adequate to
describe this system.Comment: 17 pages, 7 Figure
Effect of microstructure on the internal hydriding behavior of uranium
Please click Additional Files below to see the full abstrac
Annihilation and Control of Chiral Domain Walls with Magnetic Fields
The control of domain walls is central to nearly all magnetic technologies,
particularly for information storage and spintronics. Creative attempts to
increase storage density need to overcome volatility due to thermal
fluctuations of nanoscopic domains and heating limitations. Topological
defects, such as solitons, skyrmions, and merons, may be much less susceptible
to fluctuations, owing to topological constraints, while also being
controllable with low current densities. Here, we present the first evidence
for soliton/soliton and soliton/antisoliton domain walls in the hexagonal
chiral magnet Mn1/3NbS2 that respond asymmetrically to magnetic fields and
exhibit pair-annihilation. This is important because it suggests the
possibility of controlling the occurrence of soliton pairs and the use of small
fields or small currents to control nanoscopic magnetic domains. Specifically,
our data suggest that either soliton/soliton or soliton/antisoliton pairs can
be stabilized by tuning the balance between intrinsic exchange interactions and
long-range magnetostatics in restricted geometriesComment: 8 pages, 4 figure
Squeezing the periodicity of Néel-type magnetic modulations by enhanced Dzyaloshinskii-Moriya interaction of 4d electrons
In polar magnets, such as GaVS, GaVSe and VOSeO, modulated magnetic phases namely the cycloidal and the Néel-type skyrmion lattice states were identified over extended temperature ranges, even down to zero Kelvin. Our combined small-angle neutron scattering and magnetization study shows the robustness of the Néel-type magnetic modulations also against magnetic fields up to 2 T in the polar GaMoS. In addition to the large upper critical field, enhanced spin-orbit coupling stabilize cycloidal, Néel skyrmion lattice phases with sub-10 nm periodicity and a peculiar distribution of the magnetic modulation vectors. Moreover, we detected an additional single-q state not observed in any other polar magnets. Thus, our work demonstrates that non-centrosymmetric magnets with 4d and 5d electron systems may give rise to various highly compressed modulated states
Stripe Helical Magnetism and Two Regimes of Anomalous Hall Effect in NdAlGe
We report the magnetic and electronic transport properties of the inversion
and time-reversal symmetry breaking Weyl semimetal NdAlGe. This material is
analogous to NdAlSi, whose helical magnetism presents a rare example of a
Weyl-mediated collective phenomenon, but with a larger spin-orbit coupling. Our
neutron diffraction experiments revealed that NdAlGe, similar to NdAlSi,
supports an incommensurate Ising spin density wave ( K)
with a small helical spin canting of 3 and a long-wavelength of
35 nm, which transitions to a commensurate ferrimagnetic state below
K. Using small-angle neutron scattering, we showed that
the zero-field cooled ferrimagnetic domains form stripes in real space with
characteristic length scales of 18 nm and 72 nm parallel and perpendicular to
the [110] direction, respectively. Interestingly, for the transport properties,
NdAlSi does not exhibit an anomalous Hall effect (AHE) that is commonly
observed in magnetic Weyl semimetals. In contrast to NdAlSi, we identify two
different AHE regimes in NdAlGe that are respectively governed by intrinsic
Berry curvature and extrinsic disorders/spin fluctuations. Our study suggests
that Weyl-mediated magnetism prevails in this group of noncentrosymmetric
magnetic Weyl semimetals NdAl, but transport properties including AHE are
affected by material-specific extrinsic effects such as disorders, despite the
presence of prominent Berry curvature.Comment: Preprint, 16 pages, 6 main figures, 6 supplementary figure
Three-Dimensional Structure of Hybrid Magnetic Skyrmions Determined by Neutron Scattering
Magnetic skyrmions are topologically protected chiral spin textures which
present opportunities for next-generation magnetic data storage and logic
information technologies. The topology of these structures originates in the
geometric configuration of the magnetic spins - more generally described as the
structure. While the skyrmion structure is most often depicted using a 2D
projection of the three-dimensional structure, recent works have emphasized the
role of all three dimensions in determining the topology and their response to
external stimuli. In this work, grazing-incidence small-angle neutron
scattering and polarized neutron reflectometry are used to determine the
three-dimensional structure of hybrid skyrmions. The structure of the hybrid
skyrmions, which includes a combination of N\'eel-like and Bloch-like
components along their length, is expected to significantly contribute to their
notable stability, which includes ambient conditions. To interpret the neutron
scattering data, micromagnetic simulations of the hybrid skyrmions were
performed, and the corresponding diffraction patterns were determined using a
Born approximation transformation. The converged magnetic profile reveals the
magnetic structure along with the skyrmion depth profile, including the
thickness of the Bloch and N\'eel segments and the diameter of the core
Magnetic-field control of topological electronic response near room temperature in correlated Kagome magnets
Strongly correlated Kagome magnets are promising candidates for achieving
controllable topological devices owing to the rich interplay between inherent
Dirac fermions and correlation-driven magnetism. Here we report tunable local
magnetism and its intriguing control of topological electronic response near
room temperature in the Kagome magnet Fe3Sn2 using small angle neutron
scattering, muon spin rotation, and magnetoresistivity measurement techniques.
The average bulk spin direction and magnetic domain texture can be tuned
effectively by small magnetic fields. Magnetoresistivity, in response, exhibits
a measurable degree of anisotropic weak localization behavior, which allows the
direct control of Dirac fermions with strong electron correlations. Our work
points to a novel platform for manipulating emergent phenomena in
strongly-correlated topological materials relevant to future applications