Role of the barrier in spin-dependent tunneling addressed with superconductor spectroscopy

Kant, Ch.; Swagten, Hjm Henk; Koopmans, B.; Jonge, de Wjm Wim

doi:10.1103/physrevb.69.172408

Cited by 6 publications

(6 citation statements)

References 32 publications

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“…The spin polarization of the as-prepared sample was determined to be P = 32 ± 2 % and 34 ± 2 % for as grown and annealed junctions. This value matches the values of P = 30 ± 2 % that have been reported by Kant et al [14]. Both values appear to be Those annealed junctions exhibit tmr ratios of 410% at room temperature and 507% at low temperatures [22].…”

Section: Cobalt-based Junctionssupporting

confidence: 91%

“…The spin polarization of the as-prepared sample was determined to be P = 32 ± 2 and 33 ± 2% for as-grown and annealed junctions. This value matches the values of P = 30 ± 2% that have been reported by Kant et al [14]. Both values appear to be low when compared to TMR values of epitaxial Co(001)/MgO(001)/Co(001) junctions.…”

Section: Cobalt-based Junctionssupporting

confidence: 90%

“…If we look only at the TMR ratio and pay no attention to the SPT measurements, one half of the world cannot understand the pleasures of the other. However, only a few experiments with MgO-based systems have been reported [9,[14][15][16]. In this paper, we present SPT-experimental results on MgO-based junctions with ferromagnetic electrodes such as cobalt, Co-Fe-B and Co 2 FeAl (Heusler) and superconducting Al-Si counter electrodes.…”

Section: Introductionmentioning

confidence: 99%

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Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

et al. 2012

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We prepared magnetic tunnel junctions with one ferromagnetic and one superconducting Al-Si electrode. Pure cobalt electrodes were compared with a Co-Fe-B alloy and the Heusler compound Co 2 FeAl. The polarization of the tunneling electrons was determined using the Maki-Fulde model and is discussed along with the spin-orbit scattering and the total pair-breaking parameters. The junctions were post-annealed at different temperatures to investigate the symmetry filtering mechanism responsible for the giant tunneling magnetoresistance ratios in Co-Fe-B/MgO/Co-Fe-B junctions. 3 5. Co-Fe-B-based junctions 4 6. Co 2 FeAl-based junctions 7 7. Summary 8 Acknowledgments 8 References 9

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Section: Cobalt-based Junctionssupporting

confidence: 91%

Section: Cobalt-based Junctionssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

et al. 2012

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“…However, this type of quantitative comparison may not always be straightforward, especially for crystalline barrier and electrode interfaces such as Fe(1 0 0)/MgO(1 0 0). In such systems the F/I/F and F/I/S junctions may differ in important materials properties such as orientation and texture [20]. Consequently, the tunneling probability may depend on the orientation of the electron wave vector in ways that differ between the F/I/S and F/I/F junctions, making the analysis and comparison of effective spin polarization factors more complex and challenging.…”

Section: Tunnel Magnetoresistance and Its Bias Dependencementioning

confidence: 99%

Magnetoresistance and spin-transfer torque in magnetic tunnel junctions

Sun¹,

Ralph

2008

Journal of Magnetism and Magnetic Materials

163

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We comment on both recent progress and lingering puzzles related to research on magnetic tunnel junctions (MTJs). MTJs are already being used in applications such as magnetic-field sensors in the read heads of disk drives, and they may also be the first device geometry in which spin-torque effects are applied to manipulate magnetic dynamics, in order to make nonvolatile magnetic random access memory. However, there remain many unanswered questions about such basic properties as the magnetoresistance of MTJs, how their properties change as a function of tunnel-barrier thickness and applied bias, and what are the magnitude and direction of the spin-transfer-torque vector induced by a tunnel current.Comment: 37 pages, 2 figures. Contribution to a collection of "Current Perspectives" articles on spin transfer torque now available in the Journal of Magnetism and Magnetic Material

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“…11 Alternatively it might be of extrinsic origin, related to a lower structural quality of the tunnel barrier, e.g., caused by defects or impurities. 12,13 It is difficult to extract information on the tunneling spin polarization itself in these heavy metal oxide barriers, as shown by Kant et al 14 Instead, we will focus on the structural origin of the electron transport characteristics. In this paper we present results from a systematic study of the dependence of the MR ratio on the thickness of TaO x barrier layers.…”

Section: Introductionmentioning

confidence: 99%

Barrier thickness dependence of the magnetoresistance in TaOx magnetic tunnel junctions

Koller

Jonge

Coehoorn

2005

Journal of Applied Physics

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A systematic study has been conducted on the dependence of the magnetoresistance ͑MR͒ ratio on the barrier thickness in TaO x -based magnetic tunnel junctions. The relatively low MR ratio ͑Ͻ10% ͒ for the thinnest barriers studied decreases rapidly with increasing thickness. From Rutherford backscattering analysis and current-voltage measurements evidence for a Ta thickness dependent oxidation rate has been found. Photoconductance spectra measured on the same junctions indicate changes in the hot-electron transport into the barrier, independent of the barrier asymmetry. These changes further indicate a modification of the junction structure with increasing Ta thickness, which can have a strong adverse effect on the spin polarization of the tunnel current.

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Role of the barrier in spin-dependent tunneling addressed with superconductor spectroscopy

Cited by 6 publications

References 32 publications

Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

Magnetoresistance and spin-transfer torque in magnetic tunnel junctions

Barrier thickness dependence of the magnetoresistance in TaOx magnetic tunnel junctions

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