Condensed-Matter Physics & Materials Science Seminar

"Pressure-driven collapse of Jeff=1/2 electronic state in a honeycomb iridate"

Presented by Young-June Kim, University of Toronto, Canada

Friday, October 20, 2017, 3:00 pm — ISB Bldg. 734 Conf. Rm. 201 (upstairs)

Orbital and spin degrees of freedom in heavy transition metal compounds can be locked into each other due to strong spin-orbit coupling. The magnetism in this case is described by an effective total angular momentum jeff=1/2 rather than usual spin angular momentum. Furthermore, these jeff=1/2 moments residing on a honeycomb lattice can be coupled through bond-dependent Kitaev interactions. Magnetic properties of some honeycomb lattice iridates, such as Na2IrO3 and Li2IrO3 have been extensively investigated to examine whether Kitaev quantum spin liquid is realized in these compounds. However, the applicability of the jeff=1/2 local moment model in real materials have not been critically scrutinized experimentally. A combination of x-ray absorption spectroscopy, x-ray diffraction, and resonant inelastic x-ray scattering experiments on a honeycomb lattice Li2IrO3 reveals that the jeff=1/2 picture breaks down under high pressure, and electrons take on more itinerant character under this condition.

Hosted by: Igor Zaliznyak

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