Huge magnetoresistance and low junction resistance in magnetic tunnel junctions with crystalline MgO barrier

Tsunekawa, K.; Djayaprawira, D.D.; Yuasa, Shinji; Nagai, M.; Maehara, H.; Yamagata, S.; Okada, E.; Watanabe, Naoki; Suzuki, Y.; Ando, Koji

doi:10.1109/tmag.2005.861786

Cited by 25 publications

(8 citation statements)

References 17 publications

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“…8 In practice, such insertion can also be used for improving the crystal orientation of polycrystalline MgO leading to low resistance and high TMR ratio. 17 In this work, the interfacial and transport properties of Fe/V/MgO/Fe and Fe/V/Fe/MgO/Fe MTJs are investigated by using the ab initio nonequilibrium Green's-functions ͑NEGF͒ method implemented in the SMEAGOL code. [18][19][20] The choice of vanadium is dictated by the fact that, at variance with other transition metals, V is nonmagnetic but it can be easily polarized by proximity with a magnetic material.…”

Section: Introductionmentioning

confidence: 99%

Interface and transport properties of Fe/V/MgO/Fe and Fe/V/Fe/MgO/Fe magnetic tunneling junctions

et al. 2009

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The interface and transport properties of Fe/V/MgO/Fe and Fe/V/Fe/MgO/Fe magnetic tunneling junctions are investigated by using density-functional theory and nonequilibrium Green's-function methods. Bader analysis reveals that the Fe layer at the interface with MgO loses a small amount of charge with respect to its bulk value, in contrast to a previous study ͓W. H. Butler, X.-G. Zhang, T. C. Schulthess, and J. M. MacLaren Phys, Rev. B 63, 054416 ͑2001͔͒. At the same time at the Fe/V interface a magnetic moment is induced on the V layer by proximity. Importantly, the direction of the magnetization of the first V monolayer immediately close to the MgO barrier oscillates with the total V-layer thickness and the relative stability of a particular magnetic configuration weakens as such a thickness is increased. These two aspects pose a challenge to the Fe/V/MgO/Fe device signal stability. A more intriguing situation is found for Fe/V/Fe/MgO/Fe junctions. Their transport properties depend sensitively on the thickness of the Fe layer intercalated between V and the MgO barrier. This is the result of resonances through quantum-well states of ⌬ 1 symmetry localized in the intercalated Fe layer. In particular, for some geometries we find a massive magnetoresistance obtained by simply switching the direction of the magnetization of the Fe interlayer, while keeping the direction of the electrodes fixed. This effect may be employed in the design of new spin valves with extremely high spin polarization but still relatively large current densities.

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Section: Introductionmentioning

confidence: 99%

Interface and transport properties of Fe/V/MgO/Fe and Fe/V/Fe/MgO/Fe magnetic tunneling junctions

et al. 2009

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“…4,5 On the other hand, highly transmissive tunnel barriers are urgently needed for submillimeter mixers in order to achieve a high bandwidth, 6 in electronic refrigeration to maximize the cooling power, 7 and in high density magnetic memory devices. 8 It has been demonstrated that a major problem of amorphous AlO x barriers is that they are laterally inhomogeneous. 9,10 We take this into account by using a distribution of transparencies T n by writing for the voltageindependent normal conductance,…”

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confidence: 99%

“…In quantum computation the amorphous tunnel barrier has surfaced as an important source of decoherence leading to the introduction of an epitaxial aluminium oxide barrier [4,5]. On the other hand highly transmissive tunnel barriers are urgently needed for submillimeter mixers in order to achieve a high bandwidth [6], in electronic refrigeration to maximize the cooling power [7] and in high density magnetic memory devices [8].…”

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confidence: 99%

Epitaxial aluminum nitride tunnel barriers grown by nitridation with a plasma source

Zijlstra

Lodewijk

Vercruyssen

et al. 2007

Applied Physics Letters

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High critical current-density ͑10 to 420 kA/ cm 2 ͒ superconductor-insulator-superconductor tunnel junctions with aluminum nitride barriers have been realized using a remote nitrogen plasma from an inductively coupled plasma source operated in a pressure range of 10 −3 -10 −1 mbar. We find a much better reproducibility and control compared to previous work. From the current-voltage characteristics and cross-sectional transmission electron microscopy images it is inferred that, compared to the commonly used AlO x barriers, the polycrystalline AlN barriers are much more uniform in transmissivity, leading to a better quality at high critical current densities.

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“…4). The change in DR/R was more pronounced when the AlO x barrier was replaced by MgO with CoFeB pin and free layers [4] (Fig. 3 Besides lapping, electrostatic field associated with the bias voltage also induces a mechanical stress ð 1 2 0 r E 2 Þ in the TMR junction [2].…”

Section: Experiments and Resultsmentioning

confidence: 99%

Effects of mechanical stress on the resistance of TMR devices

Liu¹,

Jose²,

Zhu³

et al. 2007

Journal of Magnetism and Magnetic Materials

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Huge magnetoresistance and low junction resistance in magnetic tunnel junctions with crystalline MgO barrier

Cited by 25 publications

References 17 publications

Interface and transport properties of Fe/V/MgO/Fe and Fe/V/Fe/MgO/Fe magnetic tunneling junctions

Interface and transport properties of Fe/V/MgO/Fe and Fe/V/Fe/MgO/Fe magnetic tunneling junctions

Epitaxial aluminum nitride tunnel barriers grown by nitridation with a plasma source

Effects of mechanical stress on the resistance of TMR devices

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