August 11-14th at the Crowne Plaza Hotel in downtown Knoxville, TN

Engineering of magnetic chalcogenide interfaces guided by polarized neutron reflectometry

Not scheduled

20m

Crowne Plaza Knoxville

Invited Talk

Speaker

Hang Chi (University of Ottawa)

Description

Significant recent effort has been devoted in understanding the geometric aspects of condensed matter [1]. The marriage of topology and magnetism at disparate quantum interfaces, guided by polarized neutron reflectometry (PNR), constitutes an exciting arena for developing novel memory, logic and information technologies. We introduce quasi-two-dimensional (2D) magnetic transition metal chalcogenide Cr2Te3 grown by molecular beam epitaxially (MBE) as an emerging platform for spin-orbit driven Berry phenomena [2]. A unique temperature/strain modulated sign reversal of the anomalous Hall effect has been discovered and attributed to nontrivial Berry curvature physics [3]. The versatile interface tunability of Cr2Te3, when hybridized with a topological insulator [4], offers new designs for topological devices [5]. Furthermore, we observe nonreciprocity in supercurrent transport and demonstrate strong field-free superconducting diode effect in magnetic insulator/superconductor bilayers [6]. These heterostructures enable new computing regime with low energy cost, mitigating Joule heating with dissipationless supercurrent, well suited for high demanding data centers. The PNR technique is ideal in advancing the understanding of magnetic surfaces and interfaces, for exciting development of topological and superconducting spintronics.

References:
[1] H. Chi et al., Progress and prospects in the quantum anomalous Hall effect, APL Mater. 10, 090903 (2022).
[2] S. Kwon et al., Evolution of Berry phase and half-metallicity in Cr2Te3 in response to strain, filling, thickness, and surface termination, Phys. Rev. B 109, 134430 (2024).
[3] H. Chi et al., Strain-tunable Berry curvature in quasi-two-dimensional chromium telluride, Nat. Commun. 14, 3222 (2023).
[4] P. J. Taylor et al., Magnetotransport properties of ternary tetradymite films with high mobility, Mater. Today Phys. 46, 101486 (2024).
[5] Y. Ou et al., Enhanced Ferromagnetism in Monolayer Cr2Te3 via Topological Insulator Coupling, Rep. Prog. Phys. in press (2025).
[6] Y. Hou et al., Ubiquitous Superconducting Diode Effect in Superconductor Thin Films, Phys. Rev. Lett. 131, 027001 (2023).