Driving the magnetic response of BiFeO$_{3}$ by hydrostatic pressure

BiFeO$_{3}$ exhibits ferroelectric and magnetic orders at room temperature, which makes it an ideal candidate for spintronics, electro-optics and data storage applications. Most of its properties are related to its ferroelectric character, especially studied under electric or magnetic fields, however the antiferromagnetism has not been extensively investigated, in particular under pressure. Here, we bring insight into the rich spin physics of BiFeO$_{3}$ in a detailed study of the dynamic magnetic response of bulk BiFeO$_{3}$ under pressure up to 12GPa measured by Raman spectroscopy. As pressure increases, multiple spin excitations associated to non-collinear cycloidal magnetism collapse into two excitations, which show jump discontinuities at some of the ensuing crystal phase transitions. Using effective hamiltonian simulations of both the structure and the magnetism and Ginzburg-Landau theoretical calculations we show that the pressure controls both the structural phase and the magnetic anisotropy that drives the spin excitations.