Current-induced magnetization reversal in magnetic nanowires

Wegrowe, Jean-Eric; Kelly, Derek M.; Jaccard, Y.; Guittienne, Ph.; Ansermet, Jean-Philippe

doi:10.1209/epl/i1999-00213-1

Cited by 315 publications

(196 citation statements)

References 32 publications

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“…[2][3][4][5][6][7][8][9] A fairly recent research area involves magnetic nanowires, which are of potential interest for sensors and magnetic recording. 5,7,9 The present work focuses on the micromagnetic behavior of Co and Ni wires having radii of less than 10 nm.…”

Section: Introductionmentioning

confidence: 99%

Magnetic localization in transition-metal nanowires

et al. 2000

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Magnetization reversal in transition-metal nanowires is investigated. Model calculations explain why magnetization reversal is localized, as opposed to the sometimes assumed delocalized coherent-rotation and curling modes. The localization is a quite general phenomenon caused by morphological inhomogenities and occurring in both polycrystalline and single-crystalline wires. In the polycrystalline limit, the competition between interatomic exchange and anisotropy gives rise to a variety of random-anisotropy effects, whereas nearly single-crystalline wires exhibit a weak localization of the nucleation mode. Model predictions are used to explain the coercive and magnetic-viscosity behavior of Co ͑and Ni͒ nanowires electrodeposited in selfassembled alumina pores.

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Section: Introductionmentioning

confidence: 99%

Magnetic localization in transition-metal nanowires

et al. 2000

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“…The generated pure spin current enables the magnetization reversal of a nanomagnet with the same efficiency as in the case of using charge currents. These results are important for further theoretical developments in multiterminal structures 2 , but also with a view towards realizing novel devices driven by pure spin currents.In a vertical spin-valve nanopillar consisting of a ferromagnet/non-magnet/ferromagnet trilayer, the magnetic state can be switched between the antiparallel and the parallel configurations by applying a charge current [1][2][3][4][5][6][7][8][9][10][11] . This charge-current-induced magnetization switching (CIMS) is the result of a direct transfer of spin angular momentum from the spin current carried along the charge current to the localized magnetic moment in the ferromagnet.…”

mentioning

confidence: 99%

“…A spin current may interact with a magnetic nanostructure and give rise to spin-dependent transport phenomena, or excite magnetization dynamics [1][2][3][4][5][6][7][8][9][10][11] . In contrast to a spin-polarized charge current, a pure spin current does not produce any charge-related spurious effects 12,13 .…”

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Giant spin-accumulation signal and pure spin-current-induced reversible magnetization switching

2008

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A number of proposed next-generation electronic devices, including novel memory elements 1 and versatile transistor circuits 2 , rely on spin currents, that is, the flow of electron angular momentum. A spin current may interact with a magnetic nanostructure and give rise to spin-dependent transport phenomena, or excite magnetization dynamics 1-11 . In contrast to a spin-polarized charge current, a pure spin current does not produce any charge-related spurious effects 12,13 . One way to produce a pure spin current is non-local electrical-spin injection 12-18 , but this approach has suffered so far from low injection efficiency. Here, we demonstrate a significant enhancement of the non-local injection efficiency in a lateral spin valve prepared with an entirely in situ fabrication process. Improvements to the interface quality and the device structure lead to an increase of the spin-signal amplitude by an order of magnitude. The generated pure spin current enables the magnetization reversal of a nanomagnet with the same efficiency as in the case of using charge currents. These results are important for further theoretical developments in multiterminal structures 2 , but also with a view towards realizing novel devices driven by pure spin currents.In a vertical spin-valve nanopillar consisting of a ferromagnet/non-magnet/ferromagnet trilayer, the magnetic state can be switched between the antiparallel and the parallel configurations by applying a charge current [1][2][3][4][5][6][7][8][9][10][11] . This charge-current-induced magnetization switching (CIMS) is the result of a direct transfer of spin angular momentum from the spin current carried along the charge current to the localized magnetic moment in the ferromagnet. Separation of the charge and spin components raises the possibility of chargeless pure spin-current-induced magnetization switching (pure spin CIMS).The pure spin current transfers only spin angular momentum, and thus provides an attractive means to manipulate the magnetic state in magnetic nanostructures as well as a quiet electrical background for experimental studies. The pure spin current I S can be generated by the diffusion of the accumulated spins 12-20 in a metallic lateral spin-valve (LSV) structure with non-local electrical spin injection, as shown in Fig. 1a. When the spin accumulation at the interface between the permalloy (Py) and Cu wires on the detector side is non-collinear to the Py magnetization, the transverse component of the pure spin CuAu Py

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confidence: 99%

Erratum: How to build a critical mind

Beggs¹

2008

Nature Phys

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The initial observations of spin-transfer torque were made in all-metal systems [5][6][7][8][9] -that is, with two ferromagnetic metal layers separated by a non-magnetic metal. Recently, the phenomenon has also been demonstrated in magnetic tunnel junctions 10,11 (MTJs), in which the layer separating the two ferromagnetic layers is a thin insulator rather than a non-magnetic metal. In such a structure, when the magnetizations of the two ferromagnetic layers are parallel, the probability that electrons with similarly polarized spins will tunnel between them is high, and so its resistance to the flow of current is low. In contrast, when the magnetizations are antiparallel, the tunnelling probability is low and the resistance is high. The ability to distinguish the relative polarization of the two layers from their electrical resistance is one of the things that makes them attractive candidates for the basic building block of a magnetic random access memory, whose simple crosspoint architecture and non-volatile character considerably reduce the power consumption and increase the storage density. The free layer of such a structure could in principle be switched magnetically between the high and low resistance states ('1' and '0' memory states), in the same way as the bits of a magnetic hard disk are switched. But doing so without affecting the magnetization of the underlying hard layer or those of neighbouring devices is a challenging task, and one that limits the miniaturization and ultimate storage density that could be achieved. Thankfully, the spin-transfer torque effect provides an electrically driven alternative. What has been missing has been accurate information about the details of this process, a shortcoming that the two present studies address 3,4 .In the first study, Sankey and colleagues use a technique known as spin-transfer-driven ferromagnetic resonance (ST-FMR) to measure the bias-and angular-dependence of the spintransfer torque in MgO-based MTJs. In this technique the free magnetic moment of an MTJ is driven into resonance not by a microwave-frequency magnetic field, as occurs in conventional FMR, but by an electric current modulated at a microwave frequency. As this resonant dynamics is driven by the spin-transfer torque induced by the current bias, analysis of the ST-FMR signal enables the collection of detailed information on the magnitude and direction of this torque. At low currents, the authors find that the torque lies in the plane defined by the hard and free magnetizations of MTJ, and its magnitude is in excellent agreement with a prediction for highly spin-polarized tunnelling. With increasing bias, this inplane component remains large, which is quite unexpected in light of the decrease in tunnelling magnetoresistance that is observed. The authors also find that the torque vector rotates out of the plane, which may efficiently assist magnetic reversal in practical devices.In the second study, Kubota and colleagues take a similar approach but exploit the so-called spin-torque diode effec...

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Current-induced magnetization reversal in magnetic nanowires

Cited by 315 publications

References 32 publications

Magnetic localization in transition-metal nanowires

Magnetic localization in transition-metal nanowires

Giant spin-accumulation signal and pure spin-current-induced reversible magnetization switching

Erratum: How to build a critical mind

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