Excitonic Magnetism in CuFe2O4: Competing orbital and magnetic exchange energetics

CuFe2O4 belongs to a family of inverse spinels that display remarkably high magnetostrictive coefficients. CuFe2O4 is also unique in that it displays a high temperature magnetic transition followed by a lower temperature structural transition. Given the expectation that orbital physics is important and the presence of spin-orbit coupling, it is unusual for this sequence of transitions. We propose to measure the spin excitations in CuFe2O4 and apply our recently developed excitonic approach for modelling which relates the excitation spectrum to single-ion physics and in particular spin-orbit coupling. MERLIN is required given the high Curie temperature which implies a large bandwidth in the excitations and large splitting.