title: Spontaneous chiral symmetry breaking in metamaterials.
abstract: Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.
authors.affiliation: Nonlinear Physics Center and CUDOS@ANU, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Mingkai
authors.initials: M
authors.lastname: Liu
authors.affiliation: Nonlinear Physics Center and CUDOS@ANU, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Powell
authors.affiliation: Nonlinear Physics Center and CUDOS@ANU, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Ilya V
authors.initials: IV
authors.lastname: Shadrivov
authors.affiliation: CUDOS, School of Physics, University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Lapine
authors.affiliation: Nonlinear Physics Center and CUDOS@ANU, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Yuri S
authors.initials: YS
authors.lastname: Kivshar