Influence of Antiferromagnetic Ordering on Ferroelectric Polarization Switching of YMnO3 Epitaxial Thin Films

Hexagonal YMnO₃ has antiferromagnetism and ferroelectricity simultaneously below 70 K. In this study, the domain switching behavior of ferroelectric polarization at around Neel temperature is investigated. From the experimental results of the frequency and temperature dependences of coercive electric filed (Ec) obtained using polarization-electric field (P-E) hysteresis loop, the cross-correlation phenomena between magnetics and ferroelectrics are discussed in detail. The P-E hysteresis loops of the films were measured in the frequency range from 1 Hz to 10 kHz and the measurement temperature was varied from 10 to 150 K. Frequency dependence of Ec was analyzed using Ishibashi-Orihara´s theory. Change in the Ec was measured as a function of the temperature. It gradually increased with decreasing the temperature. In this regime, the change was well fitted to Devonshire´s classical theory. Below 120 K, however, it drastically increased and appart from the theory.