Giant magnetostriction in Ca2FeReO6 double perovskite

We report magnetostriction measurements in polycrystalline Ca2FeReO6 magnetic double perovskite up to 20T and in the temperature range 4.2-250K. This compound shows a high Curie temperature (TC=523K) and a structural transition at low temperatures (TS=110K). By combining magnetostriction measurements parallel and perpendicular to the magnetic field, we evaluate the anisotropic (λt) and volume magnetostriction (ω). The λt at room temperature is large and reaches below TS the giant value of ∼0.1% at 15T. Below TS, the ω is also found to be large: ∼0.05% at 15T at 5K. These results are interpreted within a scenario where the Re orbital state plays a crucial role in the ground state. The observed effect could open a new way to observe giant magnetostriction effects in transition-metal-based magnetic oxides through suitable tuning of the orbital effects in the transition metals