ECE Seminar - Topological Physics and Devices

Key Words: (topological skyrmions, magnetic multilayers, spin torques, racetrack memory)

Chiral symmetry breaking at the surfaces and interfaces are extremely important for enabling emerging topological physics, including superconductivity and magnetism. Magnetic skyrmions are real space topological spin textures that exhibit many exciting properties [1-2]. In this talk, I will first review the most recent progress in generation and manipulation of magnetic skyrmions at room temperature in the interfacially asymmetric multilayers, I will particularly show how the skyrmion Hall effect [3-5] can be used for implementing novel device applications such as skyrmion circulator and diode. Second, I will introduce a “bottom-up” method for stabilizing square and triangular skyrmion lattices by using topographically modified Si/SiO2 substrate. Based on which, an experimental realization of skyrmion shift register will be presented [6]. Lastly, through integrating skyrmions with magnetic tunnel junction (MTJ), we will demonstrate the electrical detection of mobile skyrmions by using 100% tunneling magnetoresistance (TMR) effect [7]. In the end, a few promising directions towards topological skyrmion memory will be discussed.

References:

[1]       W. Jiang, et al., Science 349, 283 (2015).

[2]        W. Jiang, et al., Physics Reports, 704, 1-49 (2017).

[3]        W. Jiang, et al., Nature Physics 13, 162 (2017).

[4]        L. Zhao, et al., Phys. Rev. Letts. 125, 027206 (2020).

[5]        C. Song, et al., Nano Letters 22, 9836 (2022).

[6]        L. Zhao, et al., Science Bulletin 69, 2370 (2024)

[7]        M. Zhao, et al., npj Quantum Materials 9, 50 (2024).