Appearance of ferroelectricity in thin SexTe1−x crystalline films

Appearance of ferroelectricity has been predicted in SexTe1−x (x=0.08–0.18) single crystalline films (thickness below 5 nm) using quantum chemical and molecular dynamics simulations. Direct measurements of the spontaneous polarization show appearance of the ferroelectricity for the film thickness below 5 nm for the selenium content x=0.10–0.30 at temperatures below 30 K. Inelastic neutron scattering and Raman measurements confirm substantial role of electron–phonon anharmonicity in the observed ferroelectric phase transition.