Magneto-ionic Composite Materials for Voltage Control of Solid-state Magnetic Devices

Technology #16956

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Professor Geoffrey Beach
Department of Materials Science and Engineering, MIT
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Uwe Bauer
Department of Materials Science and Engineering, MIT
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Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Voltage-Controlled Solid-State Magnetic Devices

US Patent Pending US 2015-0325278
Voltage-controlled domain wall traps in ferromagnetic nanowires
Nature Nanotechnology, 8 (2013) 411-416


Magnetic Tunnel Junction (MTJ) devices are used in non-volatile memory applications, such as magnetic Random Access Memory and systems that require large tunnel magneto resistances for reading sensors in hard disk drives.

Problem Addressed

Current magnetic memory devices require large currents to change the magnetic polarization of the device, which consume a significant amount of power. Previous strategies to overcome this limitation have suffered from difficult device optimization, poor temperature stability, and degradation during operation. This technology uses a gate voltage for voltage control that not only provides compatibility with voltage-based semiconductors, but also aids in switching the magnetic free layer in a MTJ. By separating the voltage functionality from the tunnel barrier through the addition of a separate voltage controlled layer, the technology reduces the required amount of current flow needed for manipulating the magnetization of the magnetic free layer. Since the technology relies on electrical voltage rather than magnetic fields or electric currents, the technology consumes less power through voltage-controlled mechanisms. 


The device described in this technology contains three main components: a thin ferromagnetic layer, a dielectric, and a metal gate electrode. The ferromagnetic layer acts as the information-storage layer as well as an electrode. The dielectric is placed between the ferromagnetic layer and the metal gate electrode to control the magnetic anisotropy in the ferromagnetic layer through the chemical composition at the interface. The metal gate electrode is made from a noble metal to avoid any unnecessary electrochemical reaction at the electrode. Application of a voltage between the two electrodes changes the magnetic properties of the ferromagnetic layer by locally modifying the magnetic anisotropy, which allows domain wall pinning. Therefore the device can achieve voltage-programmable magnetic domain walls.


  • Low power consumption
  • Compatible with CMOS technologies
  • Simple processing requirements