Spintronic devices are intensively studied to complement and to expand the operability of the CMOS transistors since they can provide new functionality as non-volatility, ultra-low power operation and scalability. The magnetic tunnel junction (MTJ) elements demonstrated the technological impact as a new type of magnetic memories, and they also have potential to be integrated in logic devices. An MTJ is formed by two magnetic layers (one of fixed magnetization acting as reference, and a layer with switchable magnetization called free layer) separated by a thin insulating barrier. The electrical resistance of these structures depends on the relative orientation of the magnetization in the two magnetic layers and it is used to encode the information. The logic operations are based on the magnetization switching and the information transport through domain walls motion.
The experimental results have shown that using the interfacial perpendicular magnetic anisotropy induced by the CoFeB/MgO interface enables the possibility to simultaneously satisfy the technological requirements of high TMR ratio for a fast and reliable reading, and low switching currents to reduce the power consumption. However, the DW velocities are rather moderate in devices based on CoFeB/MgO stacks. Recently, new engineered MTJ stacks that incorporates synthetic antiferromagnetic as free layers have been proposed. In this configuration a high domain wall velocity is expected, condition required for logic applications.
The goal of this thesis is the understanding of the magnetization switching mechanisms and the domain wall propagation in these novel devices by means of micromagnetic simulations. The study will focus on the influence of the material parameters, the thickness of the magnetic/non-magnetic layers and the device geometry on the switching behavior. The results will be used to optimize the stack composition for low switching energies and device scaling towards real applications.
Type of project: Internship, Thesis, Combination of internship and thesis
Duration: >6 Months
Required degree: Master of Engineering Technology, Master of Science, Master of Engineering Science
Required background: Nanoscience & Nanotechnology, Physics
Supervising scientist(s): For further information or for application, please contact: Van Dai Nguyen (Van.Dai.Nguyen@imec.be) and Florin Ciubotaru (Florin.Ciubotaru@imec.be) and Sebastien Couet (Sebastien.Couet@imec.be)
Only for self-supporting students.