Towards molecular spintronics

Rocha, Alexandre Reily; García‐Suárez, Víctor M.; Bailey, Steve W.; Lambert, Colin J.; Ferrer, Jaime; Sanvito, Stefano

doi:10.1038/nmat1349

Cited by 1,244 publications

(1,038 citation statements)

References 21 publications

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“…The use of spin as the information conveying entity has stirred much excitement due to its extraordinary properties of information storage, speed, and low-energy consumption [1][2][3]. Miniaturization is quickly proceeding, reaching very small domain-wall devices [4], atomic-size devices [5], and the realm of molecular devices [2,[6][7][8][9]. Among all these possibilities, antiferromagnetically (AFM) coupled devices have recently received a lot of attention.…”

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confidence: 99%

“…By studying the spectra of excitations for these chains, we can clearly separate two distinct regions in the rate due to two sets of excitations different in nature. The first region, between 6 and 12 meV, corresponds to transitions where M changes in one of the end atoms of the chain; these are very efficient in shorter chains such as Fe 6 . This type of excitation is a quantized spin wave of the finite chain [27].…”

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Correlation-Mediated Processes for Electron-Induced Switching between Néel States of Fe Antiferromagnetic Chains

et al. 2013

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The controlled switching between two quasistable Néel states in adsorbed antiferromagnetic Fe chains has recently been achieved by Loth et al. [Science 335, 196 (2012)] using tunneling electrons from an STM tip. In order to rationalize their data, we evaluate the rate of tunneling electron-induced switching between the Néel states. Good agreement is found with the experiment, permitting us to identify three switching mechanisms: (i) The search for nanoscale electronic devices has prompted intense research in the field of nanomagnetism. The use of spin as the information conveying entity has stirred much excitement due to its extraordinary properties of information storage, speed, and low-energy consumption [1][2][3]. Miniaturization is quickly proceeding, reaching very small domain-wall devices [4], atomic-size devices [5], and the realm of molecular devices [2,[6][7][8][9]. Among all these possibilities, antiferromagnetically (AFM) coupled devices have recently received a lot of attention. The AFM characteristics make these devices very well fitted for quantum computation since they naturally involved entangled states [10,11]. Moreover, the storage in AFM devices is particularly robust due to the lack of a total magnetic moment. However, this robustness has deterred their use because changing their magnetic state becomes difficult [12].Recently, Loth and co-workers succeeded in controllably switching the spin states of AFM atomic chains [12]. Two quasistable Néel states, exhibiting alternating spin directions on the atoms along the chain, were evidenced in Fe chains adsorbed on a CuN=Cuð100Þ surface. Loth and co-workers showed that the Néel states can be switched by tunneling electrons injected from a polarized scanning tunneling microscope (STM) tip into one of the atoms of the chain. This demonstrated the possibility of storing information on the atomic-scale antiferromagnet. Theoretical predictions show that writing and reading spin states entail fundamental problems associated with the quantum nature of the process [13]. Spin manipulation by tunneling electrons has been pictured as due to a spintorque mechanism where spin angular momentum from the electron is transferred into the atomic spin system [14][15][16]. However, due to the lack of magnetic moment in AFM systems, spin manipulation must follow a different mechanism. Unavoidably, spin manipulations and excitations are closely related [17]. Indeed, switching between Néel states has been experimentally associated with overcoming an activation energy [12]. However, in the case of degenerate Néel states, resonant transitions should be expected. Hence, the experimental data raise many questions regarding the possibility of resonant switching, the efficiency of activated switching, the nature of the involved excitations, and the physics at play in AFM spin torque. In summary, a complete view of the switching process is missing.In this Letter, we reveal the switching mechanisms at play in the experiment of Ref. [12]. The mechanisms turn out to be rich and ...

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Correlation-Mediated Processes for Electron-Induced Switching between Néel States of Fe Antiferromagnetic Chains

et al. 2013

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“…It is also possible to approach electronic transport problems from an atomistic viewpoint, most notably by means of ab-initio density functional theory calculations (DFT) coupled with non-equilibrium Green function methods [20,21]. However, the computational cost of these calculations can be considerably high.…”

Section: Microscopic Modellingmentioning

confidence: 99%

Electronic transport on carbon nanotube networks: A multiscale computational approach

Pereira

Ferreira

2011

Nano Communication Networks

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Carbon nanotube networks are one of the candidate materials to function as malleable, transparent, conducting films, with the technologically promising application of being used as flexible electronic displays. Nanotubes disorderly distributed in a film offers many possible paths for charge carriers to travel across the entire system, but the theoretical description of how this charge transport occurs is rather challenging for involving a combination of intrinsic nanotube properties with network morphology aspects. Here we attempt to describe the transport properties of such films in two different length scales. Firstly, from a purely macroscopic point of view we carry out a geometrical analysis that shows how the network connectivity depends on the nanotube concentration and on their respective aspect ratio. Once this is done, we are able to calculate the resistivity of a heavily disordered networked film. Comparison with experiment offers us a way to infer about the junction resistance between neighbouring nanotubes. Furthermore, in order to guide the frantic search for high-conductivity films of nanotube networks, we turn to the microscopic scale where we have developed a computationally efficient way for calculating the ballistic transport across these networks. While the ballistic transport is probably not capable of describing the observed transport properties of these films, it is undoubtedly useful in establishing an upper value for their conductivity. This can serve as a guideline in how much room there is for improving the conductivity of such networks.

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“…First-principles transport calculations, which might provide such a link, have so far focused on single molecule electronics [143,144,145], where MR effects have been demonstrated with STM [139,10,146]. Single molecules bonded to two electrodes are not, however, a good model for spintronics devices comprising molecular multilayers.…”

Section: Introductionmentioning

confidence: 99%

“…Calculations have been applied to model currents through through a single molecule attached to two FM metal electrodes [143,144,145,176,177], as they can be realized in STM experiments, for instance, where MR effects have been demonstrated at the single molecule level [10,157,146,158]. A single molecule is however not …”

Section: Introductionmentioning

confidence: 99%

Of interfaces and spin transport across nanoscale layers

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Towards molecular spintronics

Cited by 1,244 publications

References 21 publications

Correlation-Mediated Processes for Electron-Induced Switching between Néel States of Fe Antiferromagnetic Chains

Correlation-Mediated Processes for Electron-Induced Switching between Néel States of Fe Antiferromagnetic Chains

Electronic transport on carbon nanotube networks: A multiscale computational approach

Of interfaces and spin transport across nanoscale layers

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