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Fazel Tafti

Tuning competing interactions in Kitaev magnets via topochemical reactions

Tue, Nov. 8, 2022, 4:30pm
Taylor Auditorium, Frick Chemistry Lab B02
Host: Leslie Schoop

Honeycomb iridate materials have been intensely studied in the past two decades due to the potential realization of a Kitaev spin liquid phase. The basic ingredients of the Kitaev model including a honeycomb lattice, spin ½ ions, and bond-directional Ising-like interactions are present in materials such as α-Li2IrO3 and Na2IrO3. However, non-Kitaev interactions such as the Heisenberg and off-diagonal exchange are also present in real materials. These competing interactions create a complex phase diagram with non-collinear magnetic orders as well as the spin liquid phase. In this talk, we explain how topochemical methods can be used to tune the competing interactions and access different regimes in the phase diagram of Kitaev magnets. In a typical topochemical reaction, alkali ions are replaced by monovalent transition metal ions. As a result, the bond angles across the super-exchange paths change, providing a mechanism for tuning the relative strength of different exchange interactions and a potential route to discovering the quantum spin liquid phase. We will present several materials synthesized by topochemical reactions including Cu2IrO3 that exhibits a competition between static and dynamic magnetism, Ag3LiIr2O6 that exhibits thermodynamic evidence of proximity to the Kitaev spin liquid phase, and Ag3LiRh2O6 that falls is a dramatically different region of the phase diagram far from the spin liquid phase.