Search results for "magnetic anisotropy"

Kinetics of doublet formation in bicomponent magnetic suspensions: The role of the magnetic permeability anisotropy

2017

Micron-sized particles (microbeads) dispersed in a suspension of magnetic nanoparticles, i.e., ferrofluids, can be assembled into different types of structures upon application of an externalmagnetic field. This paper is devoted to theoretical modeling of a relative motion of a pair of microbeads (either soft ferromagnetic or diamagnetic) in the ferrofluid under the action of applied uniform magnetic field which induces magnetic moments in the microbeads making them attracting to each other. The model is based on a point-dipole approximation for the magnetic interactions between microbeads mediated by the ferrofluid; however, the ferrofluid is considered to possess an anisotropic magnetic p…

Coupled stochastic dynamics of magnetic moment and anisotropy axis of a magnetic nanoparticle

2012

An algorithm is developed for numerical simulation of coupled stochastic dynamics of magnetic moment and magnetic anisotropy axis of a nanoparticle. Time-correlation functions of the magnetic moment and its components longitudinal and transverse to the magnetic anisotropy axis are calculated by averaging along the stochastic trajectory. The longitudinal and transverse relaxation times are found by fitting the time correlation functions. Existing theoretical relations derived by the effective field approach in the limit of small fields are confirmed. The time-correlation functions of magnetic moments of nanoparticles in dependence on their properties are calculated numerically for arbitrary …

Photoinduced magnetization wave in diluted magnetic semiconductors

2006

We derive an evolutional equation incorporating the processes of spin-polarization transfer from an electron to a magnetic ion subsystem of a diluted magnetic semiconductor along with spin-lattice relaxation and spatial spin diffusion. Above equation has been obtained for nonequilibrium magnetization due to exchange scattering of photoexcited charge carriers by magnetic ions. We show that the mechanism of a band gap narrowing due to exchange scattering requires relatively low optical power to reach an optical bistability for pump frequency range close to crystal band gap. In a bulk crystal, only relatively small local area with essential magnetization enhancement can absorb optical power, t…

Strain-induced magnetic anisotropies in Co films on Mo(110)

2004

Giant magnetic anisotropy energy and coercivity in Fe island and atomic wire on W(110)

2012

We have directly investigated the giant magnetic anisotropy energy and coercivity of monolayer (ML) Fe islands and stripes on flat and stepped W(110) surfaces using x-ray magnetic circular dichroism. Both for islands and stripes, the magnetic anisotropy energy is $\ensuremath{\sim}$1.0 meV/atom, independent of the coverage below 0.5 ML. On the contrary, the coercive field of the islands rapidly drops from 4.3 T at 0.25 ML to 1.9 T at 0.50 ML, while that of the stripes moderately degrades from 3.5 T at 0.15 ML ($\ensuremath{\sim}$3 atom rows) to 3.0 T at 0.50 ML. We explain the contrastive behavior for the islands and stripes by different nucleation and remagnetization processes. Considering…

Electric field modification of magnetotransport in Ni thin films on (011) PMN-PT piezosubstrates

2015

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 106, 062404 (2015) and may be found at https://doi.org/10.1063/1.4907775 This study reports the magnetotransport and magnetic properties of 20 nm-thick polycrystalline Ni films deposited by magnetron sputtering on unpoled piezoelectric (011) [PbMg1/3Nb2/3O3]0.68-[PbTiO3]0.32 (PMN-PT) substrates. The longitudinal magnetoresistance (MR) of the Ni films on (011) PMN-PT, measured at room temperature in the magnetic field range of −0.3 T < μ0H < 0.3 T, is found to depend on the crystallographic direction and polarization state …

Magnetic Anisotropy Engineering in Thin Film Ni Nanostructures by Magnetoelastic Coupling

2014

Linus Pauling’s Breakthrough to the Theory of Aromatic Compounds and Hückel’s Reaction

2009

In the mid-1930s Wheland and Pauling set out to find a quantum theoretical basis for Ingold’s general electronic theory of organic reactions. A brief outline of Ingold’s main concepts will provide the necessary background for an evaluation of their contribution and Huckel’s discussion of it.

Anisotropic double exchange in orbitally degenerate mixed valence systems

2000

Abstract The problem of the double exchange is considered for the mixed valence dimers in which one or both transition metal ions possess orbitally degenerate ground states. In the pseudo-angular momentum representation, the general formula is deduced for the matrix elements of double exchange involving the transfer integrals and all spin and orbital quantum numbers. The pairs 3 T 1 t 2 2 – 2 T 2 t 2 1 and 3 T 1 t 2 2 – 4 A 2 t 2 3 are considered in three high-symmetric topologies: edge-shared D2h, corner-shared D4h, and face-shared D3h bioctahedra. The double exchange in orbitally degenerate systems is shown to produce strong magnetic anisotropy of an orbital nature. The character of the a…

Controlling the anisotropy of a van der Waals antiferromagnet with light

2020

Ultrafast optical control of magnetic anisotropy in a van der Waals antiferromagnet activates a sub-THz two-dimensional magnon.