What is the smallest storage system in the world? At the cutting edge of high-density magnetic storage media, researchers have discovered the single-atom bit, where each atom represents one bit of storage. A specific magnetization direction corresponds to the 0 bit, while the opposite direction represents the 1 bit. However, the writing and reading of a single atom's magnetization in an electrical manner pose significant challenges, impeding its real-world applications. In this talk, I will introduce the fundamental symmetry principles that guide the behaviors of electromagnetic quantities (E, H, M, σ), such as the inability of the electric field to directly switch magnetization. I will also explore how electrical current can be used to generate other axial vectors for magnetization switching, which has applications in magnetic tape, hard disk drives (HDD), and magnetic random-access memory (MRAM). Looking towards the future, the goal is to harness the spin degree of freedom while disregarding the charge degree, and to develop a system capable of generating, transporting, and storing pure spin, with low energy dissipation.
A/Prof. Liang Liu
School of Physics and Astronomy, SJTU