• Title/Summary/Keyword: tunnel magnetoresistance

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Formation of $Al_O_3$Barrier in Magnetic Junctions on Different Substrates by $O_2$Plasma Etching

  • Wang, Zhen-Jun;Jeong, Won-Cheol;Yoon, Yeo-Geon;Jeong66, Chang-Wook;Joo, Seung-Ki
    • Journal of Magnetics
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    • v.6 no.3
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    • pp.90-93
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    • 2001

  • Co/$Al_O_3$/NiFe and CO/$Al_O_3$/Co tunnel junctions were fabricated by a radio frequency magnetron sputtering at room temperature with hard mask on glass and $4^{\circ}$ tilt cut Si (111) substrates. The barrier layer was formed through two steps. After the Al layer was deposited, it was oxidized in the chamber of a reactive ion etching system (RIE) with $O_2$plasma at various conditions. The dependence of the TMR value and junction resistance on the thickness of Al layer (before oxidation) and oxidation parameters were investigated. Magnetoresistance value of 7% at room temperature was obtained by optimizing the Al layer thickness and oxidation conditions. Circular shape junctions on $4^{\circ}$tilt cut Si (111) substrate showed 4% magnetoresistance. Photovoltaic energy conversion effect was observed with the cross-strip geometry junctions on Si substrate.

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Comparison of Tunneling Characteristics in the MTJs of CoFeB/MgO/CoFeB with Lower and Higher Tunneling Magnetoresistance

  • Choi, G.M.;Shin, K.H.;Seo, S.A.;Lim, W.C.;Lee, T.D.
    • Journal of Magnetics
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    • v.14 no.1
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    • pp.11-14
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    • 2009

  • We investigated the I-V curves and differential tunneling conductance of two, CoFeB/MgO/CoFeB-based, magnetic tunnel junctions (MTJs): one with a low tunneling magnetoresistance (TMR; 22%) and the other with a high TMR (352%). This huge TMR difference was achieved by different MgO sputter conditions rather than by different annealing or deposition temperature. In addition to the TMR difference, the junction resistances were much higher in the low-TMR MTJ than in the high-TMR MTJ. The low-TMR MTJ showed a clear parabolic behavior in the dI/dV-V curve. This high resistance and parabolic behavior were well explained by the Simmons' simple barrier model. However, the tunneling properties of the high-TMR MTJ could not be explained by this model. The characteristic tunneling properties of the high-TMR MTJ were a relatively low junction resistance, a linear relation in the I-V curve, and conduction dips in the differential tunneling conductance. We explained these features by applying the coherent tunneling model.

  • https://doi.org/10.4283/JMAG.2009.14.1.011 인용 PDF KSCI

Tunneling Magnetoresistance: Physics and Applications for Magnetic Random Access Memory

  • Park, Stuart in;M. Samant;D. Monsma;L. Thomas;P. Rice;R. Scheuerlein;D. Abraham;S. Brown;J. Bucchigano
    • Proceedings of the Korean Magnestics Society Conference
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    • 2000.09a
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    • pp.5-32
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    • 2000

  • MRAM, High performance MRAM using MTJS demostrated, fully integrated MTJ MRAM with CMOS circuits, write time ~2.3 nsec; read time ~3 nsec, Thermally stable up to ~350 C, Switching field distibution controlled by size & shape. Magnetic Tunnel Junction Properties, Magnetoresistance: ~50% at room temperature, enhanced by thermal treatment, Negative and Positive MR by interface modification, Spin Polarization: >55% at 0.25K, Insensitive ot FM composition, Resistance $\times$ Area product, ranging from ~20 to 10$^{9}$ $\Omega$(${\mu}{\textrm}{m}$)$^{2}$, Spin valve transistor, Tunnel injected spin polarization for "hot" electrons, Decrease of MTJMR at high bias originates from anode.

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