FY 2019 5th Solid-State Physics Seminar

FY 2019 5th Solid-State Physics Seminar


G215-221 Seminar Room

FY 2019 5th Solid-State Physics Seminar will be held. 

Date: 9:20-10:20,Wednesday 9th October, 2019
Place: G215-221 Seminar Room
Speaker: Dr. Anjan Soumyanarayanan (A*STAR and NUS, Singapore)
Contents: Magnetic Skyrmions: Creation, Stability and Dynamics

The discovery of room temperature (RT) magnetic skyrmions in multilayer films has spawned a fascinating research field witnessing rapid progress in fundamental science and device applications [1]. A magnetic skyrmion is defined by the topological character of its spin structure, which emerges from the interplay of atomic-scale magnetic interactions. Skyrmions are expected to scale to sub-10 nm sizes, with individual addressability in devices. Here we describe our efforts to unravel the relationship between the properties of magnetic skyrmions, their parent magnetic interactions, and their stability and dynamics in multilayer thin films and devices. We begin by introducing our material platform – Ir/Fe(x)/Co(y)/Pt multilayers – wherein skyrmion properties (e.g. size, density) can be systematically tailored by varying magnetic interactions [2]. Next, we show how interfacial chiral interactions can progressively lead to the emergence of Néel helicity [3, 4], and the evolution of chiral bubbles into skyrmions [4]. Crucially, we clarify that skyrmions and chiral bubbles have distinct creation and annihilation mechanisms, which manifest in contrasting thermodynamic signatures [5]. We then turn to skyrmions in nanodots – wherein zero field stability is achieved by confinement [6]. Ongoing efforts are exploring their potential for realizing tunnel junction devices. Finally, we examine skyrmion dynamics in nanowire devices [7]. Here, we identify distinct skyrmion dynamic regimes, and distinguish intrinsic electrodynamics from geometric and disorder-related effects. We will conclude by outlining the promise of skyrmions towards nextgeneration electronic technologies.
[1] A. Soumyanarayanan et al., Nature (2016) 539, p509–517.
[2] A. Soumyanarayanan et al., Nature Materials (2017) 16, p898–904.
[3] A. Yagil et al., Applied Physics Letters (2018) 112, 192403.
[4] X. Chen et al., In Prep (2019).
[5] A.K.C. Tan et al., Submitted (2019).
[6] P. Ho et al., Physical Review Applied (2019) 11, 024064.
[7] A.K.C. Tan, P. Ho et al., In Prep (2019)

Contact Information:Yoshishige  Suzuki (D409, Graduate School of Engineering Science)