  Interactions between the constituents of a condensed matter system can drive
it through a plethora of different phases due to many-body effects. A prominent
platform for this type of behavior is a two-dimensional electron system in a
magnetic field, which evolves intricately through various gaseous, liquid and
solids phases governed by Coulomb interaction. Here we report on the
experimental observation of a phase transition between the Laughlin liquid of
composite fermions and the adjacent insulating phase of a magnetic
field-induced Wigner solid. The experiments are performed in the lowest Landau
level of a MgZnO/ZnO two-dimensional electron system with attributes of both a
liquid and a solid. An in-plane magnetic field component applied on top of the
perpendicular magnetic field extends the Wigner phase further into the liquid
phase region. Our observations indicate the direct competition between a Wigner
solid and a Laughlin liquid both formed by composite particles rather than bare
electrons.
