Annular spin-transfer memory element

Andrew D. Kent, Daniel L. Stein

    Research output: Contribution to journalArticlepeer-review


    An annular magnetic memory that uses a spin-polarized current to switch the magnetization direction or helicity of a magnetic region is proposed. The device has magnetic materials in the shape of a ring (15 nm in thickness, 20-250 nm in mean radius, and 8100 nm in width), comprising a reference magnetic layer with a fixed magnetic helicity and a free magnetic layer with a changeable magnetic helicity. These are separated by a thin nonmagnetic layer. Information is written using a current flowing perpendicular to the layers, inducing a spin-transfer torque that alters the magnetic state of the free layer. The resistance, which depends on the magnetic state of the device, is used to read out the stored information. This device offers several important advantages compared with conventional spin-transfer magnetic random access memory devices. First, the ring geometry offers stable magnetization states, which are, nonetheless, easily altered with short current pulses. Second, the ring geometry naturally solves a major challenge of spin-transfer devices: writing requires relatively high currents and a low impedance circuit, whereas readout demands a larger impedance and magnetoresistance. The annular device accommodates these conflicting requirements by performing reading and writing operations at separate read and write contacts placed at different locations on the ring.

    Original languageEnglish (US)
    Article number5282628
    Pages (from-to)129-134
    Number of pages6
    JournalIEEE Transactions on Nanotechnology
    Issue number1
    StatePublished - Jan 2011


    • Magnetic data storage
    • magnetic random access memory (MRAM)
    • spin-transfer

    ASJC Scopus subject areas

    • Computer Science Applications
    • Electrical and Electronic Engineering


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