Incipient ferroelectricity in 2.3% tensile-strained CaMnO3 films
  Epitaxial CaMnO3 films grown with 2.3% tensile strain on (001)-oriented LaAlO3 substrates are found to be incipiently ferroelectric below 25 K. Optical second harmonic generation (SHG) was used for the detection of the incipient polarization. The SHG analysis reveals that CaMnO3 crystallites with in-plane orientation of the orthorhombic b axis contribute to an electric polarization oriented along the orthorhombic a (resp.\ c) axis in agreement with the predictions from density functional calculations. 
T. G\"unter and E. Bousquet and A. David and Ph. Boullay and Ph.   Ghosez and W. Prellier and M. Fiebig
cond-mat.mtrl-sci