The Poisson Ratio in CoFe2O4 Spinel Thin Films

Michael Foerster, Milko Iliev, Nico Dix, Xavier Martí, Mykhailo Barchuk, Florencio Sánchez and Josep Fontcuberta
Adv. Funct. Mater.
Article first published online: 13 JUN 2012 | DOI: 10.1002/adfm.201200257

Epitaxial stress on thin films makes things a bit complicate. Unit cells are deformed in a non-volume conserving manner, changing interatomic bonds and ion dynamics.
Watch for the total volume variations to understand properties !