Frustrated crystallisation and melting in two-dimensional pentagonal confinement

Abstract

The crystallisation and melting behaviour of superparamagnetic colloidal particles confined within a two-dimensional pentagonal environment is studied by systematically varying either the external magnetic field or the number of particles. A system containing 16 confined particles melts monotonically from a commensurate crystalline configuration to a confined liquid-like state as the magnetic field is reduced. When the magnetic field is kept constant and the number of confined particles is increased from 11 to 21, highly non-monotonic behaviour is observed involving re-entrant structural ordering and dynamically frustrated states.