Chiral order emergence driven by quenched disorder

Quenched disorder can destroy magnetic order, for example when a random field is applied in a 2-dimensional Ising model. Even when an order exists in the presence of quenched disorder, it is usually only the survival of the order of the clean model. We present here a surprising phenomenon where an order emerges, driven by quenched disorder. This order has nothing in common with the order present in the clean model. This type of \textit{order by disorder} differs from the usual thermal or quantum one. The classical $J_1-J_3$ Heisenberg model on the kagome lattice is studied by parallel tempering Monte Carlo simulations, with site dilution. After analyzing the effect of a few vacancies 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 absence of vacancies.