Ferroelectric nanodomains in epitaxial germanium telluride thin films

Spintronics research has shown that controlling the ferroelectric polarization of innovative materials offers a way to modify the spin texture of the conduction and valence bands. This approach requires an accurate monitoring of the ferroelectric domain structure of the proposed materials. In this study we have performed the growth of germanium telluride thin films on silicon by molecular beam epitaxy in a large thickness range. We show that the volume fraction along with the size of the ferroelectric nanodomains can be controlled by finely adjusting the deposition thickness and temperature. We evidence the formation of 71°-type domain walls and in situ measurements during thermal cycling show the hysteretic appearance and decay of ferroelectric domains. A detailed analysis of the GeTe/Si interface shows that the misfit dislocations formed during the film growth plays a key role in the stability of the ferroelectric nanodomains.
This study has been conducted in collaboration with researchers from IPCMS, SOLEIL synchrotron, IM2NP and CEA-Grenoble.

Ref. :

B. Croes, F. Cheynis, Y. Zhang, C. Voulot, K. D. Dorkenoo, S. Cheri-Hertel, C. Mocuta, M. Texier, T. Cornelius, O. Thomas, M.-I. Richard, P. Mueller, S. Curiotto, and F. Leroy.