Magnetic Field induced order by disorder state selection in the classical bilayer honeycomb lattice

F. A. GÓMEZ ALBARRACÍN; H. D. ROSALES

Natal

Workshop; Latin American Workshop in Condensed Matter: Low Dimensional Topological Quantum Matter; 2015

Experimentally, in the last few years evidence of frustration has been found in Bi3Mn4O12(NO3). This material has been established as a quasi-two dimensional lattice with spin-3/2 where the Mn4+ ions are arranged in a bilayer antiferromagnetic honeycomb lattice. First principles calculations suggest the existence of weak intralayer frustrating coupling but strong interlayer coupling and possible frustration between layers. Motivated by this, in this work we present a thorough study of a classical bilayer honeycomb lattice with frustrating interlayer couplings. We show that in some particular cases this system is highly frustrated and has a degenerate ground state. We study through Monte Carlo simulations its behaviour with temperature under an external magnetic field. We find that, depending on this field, different states are selected from the ground state manifold through the order by disorder mechanism. We study different parameters to define the selected states, broken symmetries and phase transitions, and present the h-T phase diagram. Using analytical calculations and the specific heat curve simulations, we show that there are soft and zero modes in the thermal fluctuations of different states, which give rise to their selection due to order by disorder.