Magnetic field enhanced structural instability in EuTiO3.

EuTiO(3) undergoes a structural phase transition from cubic to tetragonal at T(S) = 282 K which is not accompanied by any long range magnetic order. However, it is related to the oxygen octahedral rotation driven by a zone boundary acoustic mode softening. Here, we show that this displacive second order structural phase transition can be shifted to higher temperatures by the application of an external magnetic field (ΔT(S) ∼ 4 K for μ(0)H = 9 T). This observed field dependence is in agreement with theoretical predictions based on a coupled spin-anharmonic-phonon interaction model.