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TT: Fachverband Tiefe Temperaturen

TT 6: Focused Session: Frontiers in Classical and Quantum Spin Liquids

TT 6.2: Topical Talk

Montag, 14. März 2011, 14:45–15:30, HSZ 03

Kitaev-Heisenberg Model on a Honeycomb Lattice: Possible Exotic Phases in Iridium Oxides A₂IrO₃ — •George Jackeli¹, Jiri Chaloupka^1,2, and Giniyat Khaliullin¹ — ¹Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — ²Department of Condensed Matter Physics, Masaryk University, Brno, Czech Republic

We discuss a spin one-half Hamiltonian on a honeycomb lattice describing the exchange interactions between Ir⁴⁺ ions in a family of layered iridates A₂IrO₃ (A=Li,Na). Depending on the microscopic parameters, the Hamiltonian interpolates between the Heisenberg and exactly solvable Kitaev models [1,2]. Exact diagonalization and a complementary spin-wave analysis [2] reveal the presence of an extended spin-liquid phase near the Kitaev limit and a conventional Néel state close to the Heisenberg limit. The two phases are separated by an unusual stripy antiferromagnetic state, which is the exact ground state of the model at the midpoint between two limits.

[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).