Study on voltage-controlled magnetic anisotropy (VCMA) for high-speed and low-power memory application

Leuven
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About a week ago

Join the state of the art spintronic memory device research in imec

Magnetic random access memory (MRAM) has various advantages to serve as next generation non-volatile memory application. Currently, information '1' and '0' are stored by changing the magnetic states are processed by spin transfer torque (STT) effect. It requires large current injection, hence large writing energy. Such energy consumption can be potentially reduced by several orders of magnitude with (the assistance of) Voltage Control of Magnetic Anisotropy (VCMA) effect, a recent discovered magneto-electric effect [1].

In a simple system for research, the thin film stack has a MgO/Ferromagnet(FM)/Heavy Metal(HM) tri-layers structure. The MgO/FM interface induces interfacial perpendicular magnetic anisotropy (iPMA) through orbitals hybridization, which provides the energy barrier for data storage. When a voltage is applied across MgO, the electron occupation at the interface is modified and the strength of iPMA is changed, so-called VCMA effect. VCMA coefficient is defined to estimate the amount of change in iPMA by the applied electric field through the MgO barrier. It should be improved significantly for practical application, to induce VCMA-induced switching while maintaining the sufficient data retention. Material exploration can go in the two different ways; materials adaptable to the MgO-based magnetic tunnel junction (MTJ) practical for application, and those completely new and not yet applicable to MTJs.

In this topic, student will:

  • Explore the materials to enhance VCMA coefficient
    • Adaptable within MgO\CoFeB MTJ stack - characterization with Hall bar structure (Anomalous Hall Effect) and nanoscale patterned MTJ device
    • ‚ÄčNew dielectric and ferromagnetic materials to form the interface - characterization with Hall bar structure (Anomalous Hall Effect) 

[1] T. Maruyama et al., "Large voltage-induced magnetic anisotropy change in a few atomic layers of iron." Nature Nanotechnology, vol 4, 2009.

 



Type of project: Combination of internship and thesis, Thesis, Internship

Required degree: Master of Science, Master of Engineering Science

Required background: Nanoscience & Nanotechnology, Materials Engineering

Supervising scientist(s): For further information or for application, please contact: Woojin Kim (Woojin.Kim@imec.be)

Imec allowance will be provided for students studying at a non-Belgian university.

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