Condensed-Matter Physics & Materials Science Seminar
"Magnon and Spin Orbital Excitation in the Honeycomb XY Antiferromagnet CoTiO3"
Presented by Bo Yuan, University of Toronto, Canada
Wednesday, March 10, 2021, 11:00 am — Bldg. 734 (Virtual Event)
Abstract: I will present our recent neutron scattering studies of magnetic excitations in the ilmenite CoTiO3, with a Co2+ magnetic sublattice formed by ABC stacked honeycomb layers. This material acquires an easy-plane A-type antiferromagnetic order below TN=38K. Despite its simple crystal and magnetic structure, this material has been recognized as an excellent model system for many interesting phenomena such as bond-dependent anisotropic spin interactions , quantum order by disorder , topological magnons  and collective spin orbital excitations . In the first part of the talk, I will discuss the low energy magnon excitations in CoTiO3, and its modelling using linear spin wave theory. Our results provide direct evidence for a dominant XY-like magnetic interaction in CoTiO3, which gives rise to a Dirac-cone like magnon dispersion observed in this material. I will also present our most recent high-resolution neutron scattering results in the presence of an in-plane magnetic field and discuss their implications on the nature of exchange anisotropy in this material. In the second part of the talk, I will present our temperature dependence study of the spin orbiton dynamics in CoTiO3, which we explained using a simple multilevel model. We found compelling evidence for mixing between the ground and excited spin orbital states in this material that are normally neglected in transition metal systems. I will conclude by discussing the importance of our results in the context of spin orbital physics in heavy transition metal materials.
 Huimei Liu et al., Phys. Rev. Lett., 125, 047201 (2020)
 M Elliot et al., Arxiv: 2007.04199 (2020)
 Bo Yuan et al., Phys. Rev. X, 10, 011062 (2020)
 Bo Yuan et al., Phys. Rev. B, 102, 134404 (2020)
Hosted by: Ian Robinson
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