1208.2416 (H. D. Rosales et al.)

Broken discrete symmetries in a frustrated honeycomb antiferromagnet    [PDF]

H. D. Rosales, D. C. Cabra, C. A. Lamas, P. Pujol, M. E. Zhitomirsky

We study the magnetic phase diagram of the $J_1$--$J_2$ Heisenberg antiferromagnet on a honeycomb lattice at the strongly frustrated point $J_2/J_1=1/2$ using large-scale Monte Carlo simulations. At low temperatures we find three different field regimes, each characterized by different broken discrete symmetries. In low magnetic fields up to $h_{c1}/J_1\approx 2.9$ the $Z_3$ rotational lattice symmetry is spontaneously broken while a 1/2-magnetization plateau is stabilized around $h_{c2}/J_1=4$. The collinear plateau state and the coplanar state in higher fields break the $Z_4$ translational symmetry and correspond to triple-$q$ magnetic structures. The intermediate phase $h_{c1}View original: http://arxiv.org/abs/1208.2416