title: Critical properties of the Kitaev-Heisenberg model.
abstract: We study the critical properties of the Kitaev-Heisenberg model on the honeycomb lattice at finite temperatures that might describe the physics of the quasi-two-dimensional compounds, Na(2)IrO(3) and Li(2)IrO(3). The model undergoes two phase transitions as a function of temperature. At low temperature, thermal fluctuations induce magnetic long-range order by the order-by-disorder mechanism. This magnetically ordered state with a spontaneously broken Z(6) symmetry persists up to a certain critical temperature. We find that there is an intermediate phase between the low-temperature, ordered phase and the high-temperature, disordered phase. Finite-sized scaling analysis suggests that the intermediate phase is a critical Kosterlitz-Thouless phase with continuously variable exponents. We argue that the intermediate phase has been observed above the low-temperature, magnetically ordered phase in Na(2)IrO(3), and also, likely exists in Li(2)IrO(3).
authors.affiliation: Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, Wisconsin 53706, USA.
authors.forename: Craig C
authors.initials: CC
authors.lastname: Price
authors.forename: Natalia B
authors.initials: NB
authors.lastname: Perkins