Giant Magnetostriction Due to Jahn-Teller Distortion inFe2TiO4

An anomalously large magnetostriction has been found in ${\mathrm{Fe}}_2$Ti${\mathrm{O}}_4$. The magnetostriction constants ${\lambda }_{100}$ and ${\lambda }_{111}$ are (4.7 ± 0.4) × ${10}^{-3\mathrm{}}$ and (1.3 ± 0.4) × ${10}^{-3\mathrm{}}$, respectively, at 77°K. The origin of the giant magnetostriction has been found to be due to the reduction of the elastic constant $c_{11}-c_{12}$ as the result of the presence of Jahn-Teller ${\mathrm{Fe}}^{2+}$ ions in the tetrahedral site.