Phase diagrams of ferroelectric thin film with two surface layers H. Arhchoui, Y. El Amraoui, D. Mezzane and I. Luk'yanchuk Eur. Phys. J. Appl. Phys., 48 1 (2009) 10503 Published online: 04 July 2009 DOI: 10.1051/epjap/2009119