Seminar: “Spin-Orbit Coupling in Mott Insulators" Dr. George Jackeli (MPI-FKF)

Seminar: “Spin-Orbit Coupling in Mott Insulators: Unusual Interactions and Possible Exotic Phases”

Speaker: Dr. George Jackeli, Max-Planck Institute for Solid State Research, Germany

Abstract:

Over the last few years, there has been an upsurge of interest in materials in which exotic states may emerge as the result of relativistic spin-orbit interactions. We will discuss insulating iridium oxides from this perspective.

We show that the strong spin-orbit coupling, through the entanglement of spin and orbital spaces, leads to a variety of interesting Hamiltonians ranging from the Heisenberg model to the Kitaev or quantum compass models, for different lattice geometries [1]. Based on these effective Hamiltonians, we present a comprehensive theoretical study [1-3] of the rich phase behavior and dynamics observed in layered iridium oxides such as tetragonal Sr2IrO4 and Sr3Ir2O7 and hexagonal A2IrO3 (A=Na, Li). We suggest that the hexagonal iridates might be close to the  Kitaev spin-liquid state.

We also discuss the layered tetragonal vanadate Sr2VO4 and argue that magnetically-hidden octupolar order, driven by spin-orbit coupling, is realized in this compound [4].

[1] G. Jackeli and G. Khaliullin, Phys. Rev. Lett. 102, 017205 (2009).

[2] J. Chaloupka, G. Jackeli, and G. Khaliullin, Phys. Rev. Lett. 105, 027204 (2010).

[3]   J. Chaloupka, G. Jackeli, and G. Khaliullin, arXiv:1209.5100.

[4] G. Jackeli and G. Khaliullin, Phys. Rev. Lett. 103, 067205 (2009).

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