Magnetic anisotropy and anisotropic ballistic conductance of thin magnetic wires
TL;DR: The magnetocrystalline anisotropy of thin magnetic wires of iron and cobalt is quite different from the bulk phases as discussed by the authors, and the ballistic conductance of the wire depends on the direction of the applied magnetic field, i.e. shows anisotropic ballistic magnetoresistance.
About: This article is published in Journal of Magnetism and Magnetic Materials.The article was published on 2006-05-01. It has received 3 citations till now. The article focuses on the topics: Ballistic conduction in single-walled carbon nanotubes & Magnetic anisotropy.
Citations
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TL;DR: In this paper, the magnetic and electronic properties of freestanding Fe(1−x)M −Co/Ni nanowires were investigated using ab initio simulations, and the magnetic anisotropy energy of the nanowire was observed to change sign with the increase of Co and Ni content.
Abstract: Ab initio simulations are used to investigate the magnetic and electronic properties of freestanding Fe(1−x)M
x
(M = Co/Ni) nanowires. The stability of the nanowires increases with Co (Ni) addition, as seen from the increase in cohesive energy. With the addition of Co (Ni), the average magnetic moment shows a monotonic decrease, in contrast to the Slater–Pauling behavior observed in bulk Fe–Co/Ni alloys. The magnetic anisotropy energy of the nanowire is observed to change sign, from a parallel alignment of spins along the wire axis, to a perpendicular alignment with the increase of Co and Ni content. The magnetic anisotropy energy variation is seen to be correlated with the orbital moment anisotropy. The coercivity, as calculated using the Jacobs–Bean model is observed to decrease with Co (Ni) addition to the nanowire.
14 citations
01 Mar 2003
TL;DR: In this paper, the magnetic moments and magnetic anisotropy energies of finite monoatomic Co chains were calculated using the embedded-cluster technique within the Korringa-Kohn-Rostoker method.
Abstract: We present first-principles calculations of the magnetic moments and magnetic anisotropy energies of finite monoatomic ${\mathrm{Co}}_{n}$ $(1l~nl~10)$ chains deposited along the (110) direction on top of a fcc Pt(111) surface. The calculations were performed fully relativistically using the embedded-cluster technique within the Korringa-Kohn-Rostoker method. The magnetic anisotropy energy was evaluated by means of the magnetic force theorem. As a direct consequence of the reduced coordination number of the Co atoms, we found enhanced spin and orbital moments as well as enhanced anisotropy energies in the Co chains as compared to a Co overlayer on Pt(111). For the Pt atoms adjacent to the Co atoms, however, we obtained induced magnetic moments smaller than in the case of a Co monolayer on Pt(111). The moments and the contributions of the individual atoms to the magnetic anisotropy energy depend characteristically on the position within the chains, i.e., on the local environment of the individual atoms. Independent of the length of the chains we found that the easy axis is perpendicular to the surface. The size of the calculated magnetic anisotropy energy and of the anisotropy of the orbital moment fits very well to available experimental values for monoatomic Co chains deposited on a Pt(997) surface.
3 citations
01 Aug 2007
TL;DR: Martin et al. as discussed by the authors proposed a framework for the use of the SBSU Graduate School of Physics and Astronomy as a research site for the Stony Brook University Libraries in physics.
Abstract: Stony Brook University Libraries
SBU Graduate School in physics
Lawrence Martin (Dean of Graduate School), Chi-Chang Kao - Advisor
Professor, Department of Physics and Astronomy
Senior Scientist, Brookhaven National Laboratory, Christopher Jacobsen - Chairperon
Professor, Department of Physics and Astronomy, Philip Allen
Professor, Department of Physics and Astronomy, Kenneth Evans-Lutterodt
Senior Scientist, Physics, Brookhaven National Laboratory
2 citations
Cites background from "Magnetic anisotropy and anisotropic..."
...Tetragonal strain and changes in nearest-neighbor distance on the order of a percent have been theoretically predicted to have a significant impact on both spin and orbital magnetic moments [20,23]....
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...3 Å along a theoretical unit-cell wide wire [20]....
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References
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TL;DR: The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface and the results confirm theoretical predictions and are of fundamental value to understanding how magnetic an isotropy develops in finite-sized magnetic particles.
Abstract: The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum (111) are found to have a magnetic anisotropy energy of 9 millielectron volts per atom arising from the combination of unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by the platinum substrate. By assembling cobalt nanoparticles containing up to 40 atoms, the magnetic anisotropy energy is further shown to be dependent on single-atom coordination changes. These results confirm theoretical predictions and are of fundamental value to understanding how magnetic anisotropy develops in finite-sized magnetic particles.
887 citations
TL;DR: Three-dimensional switching field measurements performed on a 3 nm cobalt cluster embedded in a niobium matrix are reported, able to separate the different magnetic anisotropy contributions and evidence the dominating role of the cluster surface.
Abstract: Using a new micro-SQUID setup, we investigate magnetic anisotropy in a single 1000-atom cobalt cluster. This system opens new fields in the characterization and understanding of the origin of magnetic anisotropy in such nanoparticles. For this purpose, we report three-dimensional switching field measurements performed on a 3 nm cobalt cluster embedded in a niobium matrix. We are able to separate the different magnetic anisotropy contributions and evidence the dominating role of the cluster surface.
380 citations
TL;DR: In this paper, magnetoresistance experiments in magnetic Ni nanocontacts in the ballistic transport regime at room temperature were conducted and it was shown that the magnetoreduction for a few-atom contact reaches values of $280%$ at room-temperature and for applied magnetic fields of 100 Oe.
Abstract: We present magnetoresistance experiments in magnetic Ni nanocontacts in the ballistic transport regime at room temperature. It is shown that the magnetoresistance for a few-atom contact reaches values of $280%$ at room temperature and for applied magnetic fields of 100 Oe. Results are presented for over 50 samples showing the trend that the smaller the contact the larger the magnetoresistance response. This indicates that the effect arises just at the nanocontact.
355 citations
TL;DR: One-dimensional Co atomic wires grown on Pt(997) have been investigated by x-ray magnetic circular dichroism and the easy axis of magnetization, the magnetic anisotropy energy, and the coercive field oscillate as a function of the transverse width of the wires, in agreement with theoretical predictions for 1D metal systems.
Abstract: One-dimensional Co atomic wires grown on Pt(997) have been investigated by x-ray magnetic circular dichroism. Strong changes of the magnetic properties are observed as the system evolves from 1D- to 2D-like. The easy axis of magnetization, the magnetic anisotropy energy, and the coercive field oscillate as a function of the transverse width of the wires, in agreement with theoretical predictions for 1D metal systems.
129 citations
TL;DR: The magnetoresistance is strongly enhanced for the narrow PC and oscillates with the conductance and the sequence of quantized conductances depends on the relative orientation of magnetizations between left and right electrodes.
Abstract: We theoretically study the electron transport through a magnetic point contact (PC) with special attention given to the effect of an atomic scale domain wall (DW). The spin precession of a conduction electron is forbidden in such an atomic scale DW and the sequence of quantized conductances depends on the relative orientation of magnetizations between left and right electrodes. The magnetoresistance is strongly enhanced for the narrow PC and oscillates with the conductance.
108 citations