Duck-Ho Kim

Affiliation: Korea Institute of Science and Technology (KIST)

Research interests: Spintronics

Title: Spin Transport and Dynamics in Ferrimagnetic Materials

Abstract: The dynamic phenomena of topological spin objects in magnetic materials have been actively studied not only for their academic interest but also for their potential applications in next – generation memory devices [1 – 4]. Representative topological spin objec ts include chiral magnetic domain walls [1, 2] and magnetic skyrmions [3, 4]. It is possible to manipulate topological spin objects using electric current, and the underlying mechanism involves the conservation of angular momentum arising from the interact ion between the electron’s spin and the spin of the phase spin structure as the electron traverses the magnetic material [5, 6]. This interaction is known as spin torque and can be divided into spin – transfer torque and spin – orbit torque depending on the tr ansmitting materials . Recently, ultrafast motion of topological spin objects has been predicted in antiferromagnetic materials (total magnetization = 0) through theoretical studies [7]. Unfortunately, antiferromagnetic materials are difficult to measure (t otal magnetization = 0) and challenging to control (due to strong coupling energy), making it difficult to experimentally verify the theory. However, in the case of ferrimagnetic materials, which have a finite magnetization at the angular momentum compensa tion point where the angular momentum is zero, it has been possible to investigate the spin dynamics of antiferromagnetic materials. With this possibility, ultrafast motion has been observed at the angular momentum compensation point when topological spin objects are driven by a magnetic field [8]. In this presentation, we will discuss the spin transfer torque phenomenon [9] and the phenomenon of skyrmion hall effect [10] at the angular momentum compensation point when topological spin structures is driven by electric current in ferrimagnetic materials