Enhanced magnetoresistance of permalloy/Al-oxide/cobalt tunnel junctions in the Coulomb blockade regime

Brückl, Hubert; Reiss, Günter; Vinzelberg, H.; Bertram, M.; Mönch, Ingolf; Schumann, J.

doi:10.1103/physrevb.58.r8893

Cited by 50 publications

(24 citation statements)

References 20 publications

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“…A typical example is a ferromagnetic single-electron transistor, i.e., a small metallic nanoparticle (semiconducting quantum dots or molecules are also possible) coupled by tunnel barriers to ferromagnetic electrodes [23,24]. First ferromagnetic single-electron transistors were fabricated by Ono et al [25,26] and later by Brückl et al [27]. Transport in ferromagnetic single-electron transistors with nonmagnetic metallic islands -both normal and superconducting -was also measured [28,29,30,31].…”

Section: Introductionmentioning

confidence: 99%

Spin effects in single-electron tunnelling

Barnaś¹,

Weymann²

2008

J. Phys.: Condens. Matter

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Abstract. An important consequence of the discovery of giant magnetoresistance in metallic magnetic multilayers is a broad interest in spin dependent effects in electronic transport through magnetic nanostructures. An example of such systems are tunnel junctions -single-barrier planar junctions or more complex ones. In this review we present and discuss recent theoretical results on electron and spin transport through ferromagnetic mesoscopic junctions including two or more barriers. Such systems are also called ferromagnetic single-electron transistors. We start from the situation when the central part of a device has the form of a magnetic (or nonmagnetic) metallic nanoparticle. Transport characteristics reveal then single-electron charging effects, including the Coulomb staircase, Coulomb blockade, and Coulomb oscillations. Single-electron ferromagnetic transistors based on semiconductor quantum dots and large molecules (especially carbon nanotubes) are also considered. The main emphasis is placed on the spin effects due to spin-dependent tunnelling through the barriers, which gives rise to spin accumulation and tunnel magnetoresistance. Spin effects also occur in the current-voltage characteristics, (differential) conductance, shot noise, and others. Transport characteristics in the two limiting situations of weak and strong coupling are of particular interest. In the former case we distinguish between the sequential tunnelling and cotunnelling regimes. In the strong coupling regime we concentrate on the Kondo phenomenon, which in the case of transport through quantum dots or molecules leads to an enhanced conductance and to a pronounced zero-bias Kondo peak in the differential conductance.

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Section: Introductionmentioning

confidence: 99%

Spin effects in single-electron tunnelling

Barnaś¹,

Weymann²

2008

J. Phys.: Condens. Matter

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“…In a FM-QD-FM system the quantum dot plays a role in the transport properties, thus giving rise to new physics not present in the usual FM-I-FM junction. For example, this system can exhibit Coulomb blockade [6]- [8] and the Kondo effect [9]- [11] In this work, we are particularly interested in the interplay of spin-flip scattering and electron-electron interaction effects on the TMR. We assume that both the spin flip and Coulomb correlations act only within the dot.…”

Section: Introductionmentioning

confidence: 99%

TMR effect in a FM-QD-FM system

2004

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Using the Keldysh nonequilibrium technique, we study current and the tunnelling magnetoresistance (TMR) in a quantum dot coupled to two ferromagnetic leads (FM-dot-FM). The current is calculated for both parallel and antiparallel lead alignments. Coulomb interaction and spin-flip scattering are taken into account within the quantum dot. Interestingly, we find that these interactions play a contrasting role in the TMR: there is a parameter range where spin flip suppresses the TMR, while Coulomb correlations enhance it, due to Coulomb blockade.

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“…Brückl et al [77] also observed a TMR enhancement at low bias in nanoscale Co/AlO x /NiFe junctions prepared by variable angle evaporation, while Zhu & Wang [78] observed a similar effect in a sputtered Fe-Al 2 O 3 granular film. In all these cases, the effect is explained by the coherence in electron motion to be found in the higher order tunnelling processes that are still possible when the usual sequential tunnelling process is forbidden.…”

Section: (E) Tunnelling Magnetoresistance Enhancement By Cotunnellingmentioning

confidence: 87%

Single electron spintronics

Dempsey

Ciudad

Marrows

2011

Phil. Trans. R. Soc. A.

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Single electron electronics is now well developed, and allows the manipulation of electrons one-by-one as they tunnel on and off a nanoscale conducting island. In the past decade or so, there have been concerted efforts in several laboratories to construct single electron devices incorporating ferromagnetic components in order to introduce spin functionality. The use of ferromagnetic electrodes with a non-magnetic island can lead to spin accumulation on the island. On the other hand, making the dot also ferromagnetic introduces new physics such as tunnelling magnetoresistance enhancement in the cotunnelling regime and manifestations of the Kondo effect. Such nanoscale islands are also found to have long spin lifetimes. Conventional spintronics makes use of the average spin-polarization of a large ensemble of electrons: this new approach offers the prospect of accessing the quantum properties of the electron, and is a candidate approach to the construction of solid-state spin-based qubits.

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Enhanced magnetoresistance of permalloy/Al-oxide/cobalt tunnel junctions in the Coulomb blockade regime

Cited by 50 publications

References 20 publications

Spin effects in single-electron tunnelling

Spin effects in single-electron tunnelling

TMR effect in a FM-QD-FM system

Single electron spintronics

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