We discovered from first principles an unusual polar state in the low Ruddlesden-Popper (RP) layered perovskites in which ferroelectricity is nearly degenerate with antiferroelectricity, a relatively rare form of ferroic order. We show that epitaxial strain plays a key role in tuning the “perpendicular coherence length” of the ferroelectric mode, and does not induce ferroelectricity in these low-dimensional RP materials as is well known to occur in . These systems present an opportunity to manipulate the coherence length of a ferroic distortion in a controlled way, without disorder or a free surface.
- Received 7 October 2011
- Corrected 27 December 2011
© 2011 American Physical Society