Electric spontaneous polarization in YbFe_2O_4

摘要

We report the observation of the electric spontaneous polarization in YbFe_2O_4, one candidate "electronic ferroelectric," where ferroelectricity originates from the polar charge order. Though we have proposed that in LuFe_2O_4 polar charge ordering of iron ions having different valence states give rise to ferroelectricity, some reports questioned not only the electronic origin but also the existence of the ferroelectricity itself in this system. In response to this, we show a direct macroscopic evidence of the existence of the ferroelectricity by a clear P-E hysteresis loop of YbFe_2O_4 belonging to the same system as that of LuFe_2O_4. Although further investigations are required about the electronic origin, we report the direct observation of the macroscopic electric polarization.