Voltage-controlled magnetic anisotropy (VCMA) for high-speed and low-power memory application

Leuven - Master projects/internships
More than two weeks ago

Voltage-controlled magnetic anistoropy will enable beyond GHz writing in spintronic devices above STT-MRAM.

Magnetic random access memory (MRAM) has multiple advantages to serve as next generation non-volatile cache memory. Currently, the magnetic states '1' and '0' are processed by spin transfer torque (STT) effect, which requires large current injection and 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 stack has a MgO/Ferromagnet(FM)/Metal(M) 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. The present VCMA effect is however not sufficient for practical application. To achieve VCMA switching while maintaining enough retention, an improvement of VCMA coefficient of at least 5 times is required. Improving methods have been widely proposed, but to keep the essential stack materials for MTJ, adding dusting layer to the MgO/FM interface is more a practical treatment.

In this topic, student will:

  • Explore the influence of dusting materials to the magnetic properties and seek for the potential dusting materials to enhance the VCMA effect.
  • Characterization of VCMA properties with Anomalous Hall Effect through self-fabricated Hall bar structures.
  • Implement the well performed stacks into the state-of-the-art MTJ as final demonstration.

Depending on interest, student can also

  • Design new masks for UV lithography and for more reliable AHE measurement

[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: Internship, Combination of internship and thesis

Duration: > 6 month

Required degree: Master of Science, Master of Engineering Science

Required background: Electrotechnics/Electrical Engineering, Nanoscience & Nanotechnology

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

Imec allowance will be provided

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