Jagath Gunasekera, Owen P. Vajk, Yuan Wang, Kevin Tarwater, Tom W. Heitmann
Strong magnetic-ferroelectric coupling in hexagonal HoMnO3 has been observed previously at spin reorientation temperature between P6'3cm' and the P6'3cm' magnetic phases. In contrast, YMnO3 has only a single magnetic phase (P6'3cm') and no sign of strong magnetic-ferroelectric coupling. In order to investigate the P6'3cm' to P6'3c'm spin reorientation transition, single crystals of Ho(1-x)YxMnO3 at varying compositions were grown. Neutron scattering measurements reveal quasielastic scattering in the YMnO3-like phase (P6'3c'm) centered on the Bragg peak corresponding to HoMnO3-like phase (P6'3cm') and vice versa. This scattering may be due to short-lived fluctuations into the "wrong" magnetic phase at domain boundaries. These results suggest that there is strong phase competition between the P6'3cm' and P6'3c'm phases even in pure YMnO3, and this competition may play an important role in the magnetic-ferroelectric coupling observed in HoMnO3.
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http://arxiv.org/abs/1303.5791
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