68 research outputs found
Nonlinear Decay of Quantum Confined Magnons in Itinerant Ferromagnets
Quantum confinement leads to the emergence of several magnon modes in
ultrathin layered magnetic structures. We probe the lifetime of these quantum
confined modes in a model system composed of three atomic layers of Co grown on
different surfaces. We demonstrate that the quantum confined magnons exhibit
nonlinear decay rates, which strongly depend on the mode number, in sharp
contrast to what is assumed in the classical dynamics. Combining the
experimental results with those of linear-response density functional
calculations we provide a quantitative explanation for this nonlinear damping
effect. The results provide new insights into the decay mechanism of spin
excitations in ultrathin films and multilayers and pave the way for tuning the
dynamical properties of such structures
Exchange interaction and its tuning in magnetic binary chalcogenides
Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.Using a first-principles Green's function approach we study magnetic properties of the magnetic binary tetradymite chalcogenides Bi2Se3, Bi2Te3, and Sb2Te3. The magnetic coupling between transition-metal impurities is long range, extends beyond a quintuple layer, and decreases with increasing number of d electrons per 3d atom. We find two main mechanisms for the magnetic interaction in these materials: the indirect exchange interaction mediated by free carriers and the indirect interaction between magnetic moments via chalcogen atoms. The calculated Curie temperatures of these systems are in good agreement with available experimental data. Our results provide deep insight into exchange interactions in magnetic binary tetradymite chalcogenides and open a way to design new materials for promising applications.We acknowledge support by the Tomsk State University Competitiveness Improvement Program and the Deutsche Forschungsgemeinschaft (Priority Program SPP 1666 “Topological Insulators”).Peer Reviewe
Exchange interaction and its tuning in magnetic binary chalcogenides
Using a first-principles Green's function approach we study magnetic
properties of the magnetic binary chalcogenides Bi2Te3, Bi2Se3, and Sb2Te3. The
magnetic coupling between transition-metal impurities is long-range, extends
beyond a quintuple layer, and decreases with increasing number of d electrons
per 3d atom. We find two main mechanisms for the magnetic interaction in these
materials: the indirect exchange interaction mediated by free carriers and the
indirect interaction between magnetic moments via chalcogen atoms. The
calculated Curie temperatures of these systems are in good agreement with
available experimental data. Our results provide deep insight into magnetic
interactions in magnetic binary chalcogenides and open a way to design new
materials for promising applications
The optical tweezer of skyrmions
In a spin-driven multiferroic system, the magnetoelectric coupling has the form of effective dynamical Dzyaloshinskii–Moriya (DM) interaction. Experimentally, it is confirmed, for instance, for Cu2OSeO3, that the DM interaction has an essential role in the formation of skyrmions, which are topologically protected magnetic structures. Those skyrmions are very robust and can be manipulated through an electric field. The external electric field couples to the spin-driven ferroelectric polarization and the skyrmionic magnetic texture emerged due to the DM interaction. In this work, we demonstrate the effect of optical tweezing. For a particular configuration of the external electric fields it is possible to trap or release the skyrmions in a highly controlled manner. The functionality of the proposed tweezer is visualized by micromagnetic simulations and model analysis
Ab initio design of quaternary Heusler compounds for reconfigurable magnetic tunnel diodes and transistors
Reconfigurable magnetic tunnel diodes and transistors are a new concept in
spintronics. The realization of such a device requires the use of materials
with unique spin-dependent electronic properties such as half-metallic magnets
(HMMs) and spin-gapless semiconductors (SGSs). Quaternary Heusler compounds
offer a unique platform to design within the same family of compounds HMMs and
SGSs with similar lattice constants to make coherent growth of the consecutive
spacers of the device possible. Employing state-of-the-art first-principles
calculations, we scan the quaternary Heusler compounds and identify suitable
candidates for these spintronic devices combining the desirable properties: (i)
HMMs with sizable energy gap or SGSs with spin gaps both below and above the
Fermi level, (ii) high Curie temperature, (iii) convex hull energy distance
less than 0.20 eV, and (iv) negative formation energies. Our results pave the
way for the experimental realization of the proposed magnetic tunnel diodes and
transistors.Comment: 13 pages, 9 figure
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