THERMODYNAMICS OF TUNABILITY IN (Bao6oSio4o)Ti03 THIN FILMS

摘要

The misfit dependence of tunability in the prototypical paraelectric barium strontium titanate is investigated theoretically. We propose a self-consistent thermodynamic potential, by which we analyze the tunability in BST 60/40 thin films on cubic tensile and compressive substrates. We then quantitatively explain the origins misfit dependence of tunability in such paraelectric thin films, and indicate the inverse relation between magnitude of the misfit strain and tunability. We also explain the singularity observed in tunability around zero-misfit, and assert that one needs to take the orientation of the unit cell under the effect of the misfit into consideration.