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Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers

Nature Materials volume 3, pages 862–867 (2004)Cite this article

Abstract

Magnetically engineered magnetic tunnel junctions (MTJs) show promise as non-volatile storage cells in high-performance solid-state magnetic random access memories (MRAM)1. The performance of these devices is currently limited by the modest (<∼70%) room-temperature tunnelling magnetoresistance (TMR) of technologically relevant MTJs. Much higher TMR values have been theoretically predicted for perfectly ordered (100) oriented single-crystalline Fe/MgO/Fe MTJs. Here we show that sputter-deposited polycrystalline MTJs grown on an amorphous underlayer, but with highly oriented (100) MgO tunnel barriers and CoFe electrodes, exhibit TMR values of up to ∼220% at room temperature and ∼300% at low temperatures. Consistent with these high TMR values, superconducting tunnelling spectroscopy experiments indicate that the tunnelling current has a very high spin polarization of ∼85%, which rivals that previously observed only using half-metallic ferromagnets2. Such high values of spin polarization and TMR in readily manufactureable and highly thermally stable devices (up to 400 °C) will accelerate the development of new families of spintronic devices.

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Figure 1: Giant room-temperature TMR.
Figure 2: Highly oriented (100) MgO tunnel barrier.
Figure 3: Anneal dependence of TMR and RA measured using the current-in-plane tunnelling measurement technique on an unpatterned MTJ film.
Figure 4: Temperature dependence of TMR (filled circles) and RA (squares) for the same magnetic tunnel junctions shown in Fig. 1.
Figure 5: Measurement of tunnelling spin-polarization.

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Acknowledgements

We thank Daniel Worledge for the CIPT measurements. Christian Kaiser is also at RWTH Aachen, Physikalisches Institut (IIA), 52056 Aachen, Germany. This work is partially supported by the DARPA spintronics and SPINS programs.

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Authors and Affiliations

  1. IBM Research Division, IBM Almaden Research Center, IBM-Infineon MRAM Development Alliance, 650 Harry Road, San Jose, 95120, California, USA

    Stuart S. P. Parkin, Christian Kaiser, Alex Panchula, Philip M. Rice, Mahesh Samant & See-Hun Yang

  2. Infineon Technologies, IBM Almaden Research Center, IBM-Infineon MRAM Development Alliance, 650 Harry Road, San Jose, 95120, California, USA

    Brian Hughes

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Correspondence to Stuart S. P. Parkin.

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Parkin, S., Kaiser, C., Panchula, A. et al. Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers. Nature Mater 3, 862–867 (2004). https://doi.org/10.1038/nmat1256

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