Search results for "53"
showing 10 items of 2908 documents
Spin-orbit torques in locally and globally non-centrosymmetric crystals: Antiferromagnets and ferromagnets
2016
One of the main obstacles that prevents practical applications of antiferromagnets is the difficulty of manipulating the magnetic order parameter. Recently, following the theoretical prediction [J. \v{Z}elezn\'y et al., PRL 113, 157201 (2014)], the electrical switching of magnetic moments in an antiferromagnet has been demonstrated [P. Wadley et al., Science 351, 587 (2016)]. The switching is due to the so-called spin-orbit torque, which has been extensively studied in ferromagnets. In this phenomena a non-equilibrium spin-polarization exchange coupled to the ordered local moments is induced by current, hence exerting a torque on the order parameter. Here we give a general systematic analys…
Orbitronics: orbital currents in solids
2021
In solids, electronic Bloch states are formed by atomic orbitals. While it is natural to expect that orbital composition and information about Bloch states can be manipulated and transported, in analogy to the spin degree of freedom extensively studied in past decades, it has been assumed that orbital quenching by the crystal field prevents significant dynamics of orbital degrees of freedom. However, recent studies reveal that an orbital current, given by the flow of electrons with a finite orbital angular momentum, can be electrically generated and transported in wide classes of materials despite the effect of orbital quenching in the ground state. Orbital currents also play a fundamental …
Band structure tuning of Heusler compounds: Spin- and momentum-resolved electronic structure analysis of compounds with different band filling
2019
Physical review / B 103(5), 054407 (2021). doi:10.1103/PhysRevB.103.054407
Thermally induced magnon accumulation in two-sublattice magnets
2016
We present a temperature-dependent study of the thermal excitation of a magnon accumulation in two-sublattice magnetic materials. Using atomistic spin model simulations, we study the local magnetization profiles sublattice-wise in the vicinity of a temperature step in antiferromagnets, as well as in ferrimagnets. It is shown that the strength of the magnon accumulation in these systems scales with the derivative of the magnetization with respect to the temperature. These results give an insight into the complex temperature dependence of the magnon accumulation by making a direct link to the macroscopic behavior of the magnetization.
Distinct magnetotransport and orbital fingerprints of chiral bobbers
2019
While chiral magnetic skyrmions have been attracting significant attention in the past years, recently, a new type of a chiral particle emerging in thin films $-$ a chiral bobber $-$ has been theoretically predicted and experimentally observed. Here, based on theoretical arguments, we provide a clear pathway to utilizing chiral bobbers for the purposes of future spintronics by uncovering that these novel chiral states possess inherent transport fingerprints that allow for their unambiguous electrical detection in systems comprising several types of chiral states. We reveal that unique transport and orbital characteristics of bobbers root in the non-trivial magnetization distribution in the …
Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy
2016
Magnetic skyrmions are highly promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their finite topological charge leads to a predicted "skyrmion Hall effect", in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we present nanoscale pump-probe imaging that for the first time reveals the real-time dynamics of skyrmions driven by current-induced spin orbit torque (SOT). We…
Mixed topology ring states for Hall effect and orbital magnetism in skyrmions of Weyl semimetals
2020
Skyrmion lattices as a novel type of chiral spin states are attracting increasing attention, owing to their peculiar properties stemming from real-space topological properties. At the same time, the properties of magnetic Weyl semimetals with complex $k$-space topology are moving into the focus of research in spintronics. We consider the Hall transport properties and orbital magnetism of skyrmion lattices imprinted in topological semimetals, by employing a minimal model of a 2D mixed Weyl semimetal which, as a function of the magnetization direction, exhibits two Chern insulator phases separated by a Weyl state for an an in-plane magnetization direction. We find that while the orbital magne…
Evidence for phonon skew scattering in the spin Hall effect of platinum
2018
We measure and analyze the effective spin Hall angle of platinum in the low-residual resistivity regime by second-harmonic measurements of the spin-orbit torques for a multilayer of $\mathrm{Pt}|\mathrm{Co}|{\mathrm{AlO}}_{x}$. An angular-dependent study of the torques allows us to extract the effective spin Hall angle responsible for the damping-like torque in the system. We observe a strikingly nonmonotonic and reproducible temperature dependence of the torques. This behavior is compatible with recent theoretical predictions which include both intrinsic and extrinsic (impurities and phonons) contributions to the spin Hall effect at finite temperatures.
The growth of atomically rough 4He crystals
1986
We have studied the growth of atomically rough bcc and hcp4He crystals from the superfluid phase for temperaturesT>0.9 K. The growth coefficient displays a temperature dependence which can be represented bym 4 K∝ $$e^{\Delta E/k_B T} $$ . The parameter ΔE is found to be in close agreement with the energy gap of rotons, suggesting that these thermal excitations dominate the growth kinetics. Besides, the absolute value of the growth coefficient depends on crystal orientation, with an anisotropy for the hcp phase of about a factor of 2.5 between the $$\left\{ {10\bar 10} \right\}$$ and {0001} planes.
Close packing of clusters: Application toAl100
2003
The lowest energy configurations of close-packed clusters up to N=110 atoms with stacking faults are studied using the Monte Carlo method with Metropolis algorithm. Two types of contact interactions, a pair-potential and a many-atom interaction, are used. Enhanced stability is shown for N=12, 26, 38, 50, 59, 61, 68, 75, 79, 86, 100 and 102, of which only the sizes 38, 75, 79, 86, and 102 are pure FCC clusters, the others having stacking faults. A connection between the model potential and density functional calculations is studied in the case of Al_100. The density functional calculations are consistent with the experimental fact that there exist epitaxially grown FCC clusters starting from…