F-model phase transition in spin ice thin films

Spin ice is an exotic magnet known for its magnetic monopole excitations and disordered magnetic ground state. This is an experiment on half micron thick epitaxial films of spin ice, that behave like bulk spin ice under in-plane compression. Specific heat measurements suggest that this leads to an unusual phase transition from the disordered spin ice state (the magnetic monopole vacuum) to an ordered state. Such a phase transition is known in the "F-model" of statistical mechanics, but never hitherto observed in a magnetic material. The aim of this experiment is to measure magnetic Bragg peaks that should evolve at temperature below the transition and to map pout the phase diagram by measuring magnetic Bragg peaks as a function of applied magnetic field. In this way we will determine the magnetic order and phase diagram of this interesting system.