Field induced phase transition in the classical honeycomb Gamma model

Recent studies have indicated the importance of the symmetric aniostropic exchange interaction, also called the Γ term, in the so-called Kitaev materials. Moreover, a new type of classical spin liquid was shown to be the ground state of the classical Γ model on the honeycomb lattice [1]. In our previous paper [2], we further demonstrated that thermal order-by-disorder drives the system toward a novel plaquette ordering that spontaneously breaks the lattice translation symmetry. In this work, we study the effects of magnetic field on the plaquette-ordered state. Our extensive Monte Carlo simulations uncover a field-induced phase transition above which the √3×√3 flux order is replaced by a new spin order. We will present our characterization of this intermediate phase and discuss the nature of the phase transitions. [1] I. Rousochatzakis and N. B. Perkins, Phys. Rev. Lett. 118, 147204 (2017). [2] P. Saha, Z. Fan, D. Zhang, and G.-W. Chern, Phys. Rev. Lett. 122, 257204 (2019).