We fabricated epitaxial thin films of hexagonal DyMnO3, which otherwise form in a bulk perovskite structure, via deposition on Pt(111)//Al2O3 (0001) and YSZ(111) substrates: each of which has in-plane hexagonal symmetry. The polarization hysteresis loop demonstrated the existence of ferroelectricity in our hexagonal DyMnO3 films at least below 70 K. The observed 2.2 uC/cm^2 remnant polarization at 25 K corresponded to a polarization enhancement by a factor of 10 compared to that of the bulk orthorhombic DyMnO3. Interestingly, this system showed an antiferroelectric-like feature in its hysteresis loop. Our hexagonal DyMnO3 films showed an antiferromagnetic Neel temperature around 60 K and a spin reorientation transition around 40 K. We also found a clear hysteresis in the temperature dependence of the magnetization, which was measured after zero-field-cooling and field-cooling. This hysteresis may well have been of spin glass origin, which was likely to arise from the geometric frustration of antiferromagnetically-coupled Mn spins with an edge-sharing triangular lattice.
@article{arxiv.cond-mat/0610681,
title = {Multiferroic properties of epitaxially stabilized hexagonal DyMnO3 thin films},
author = {J. -H. Lee and P. Murugavel and D. Lee and T. W. Noh and Y. Jo and M. -H. Jung and K. H. Jang and J. -G. Park},
journal= {arXiv preprint arXiv:cond-mat/0610681},
year = {2015}
}