Chiral order emergence driven by quenched disorder

Quenched disorder is expected to destroy order, such as when a random field is applied in a 2-dimensional magnetic system. Even when order exists in the presence of disorder, it is usually only the survival of the order of the clean model. We present here a surprising phenomenon where an order, driven by quenched disorder, emerges, that has nothing in common with the order present in the clean model. It's a new type of order by disorder that differs from the usual thermal or quantum one. The classical Heisenberg model on the $J_1-J_3$ kagome lattice is studied by parallel tempering Monte Carlo simulations, with magnetic site vacancies. After analyzing the effect of a few impurities on the ground state, favoring non-coplanar configurations, we show the emergence of a low-temperature chiral phase and the progressive destruction of the collinear $q=4$ Potts order, the only order present in the clean system.