κ-Al2O3-type structure (Pna21) is composed of close-packed oxygen layers with a sequence of ABACABAC…… , and has alternative stacking of spinel and corundum layers along c-axis. Cations in the mid-oxygen layers have four sites of one tetrahedral and three octahedral sites. Under the electric field applied along c-axis, oxygen layers in the corundum layer shift along ±a-axis to yield a shear in the spinel layer, subsequently, coordination of cations in octahedral/tetrahedral sites in the spinal layer change to tetrahedral/octahedral ones to cause a polarization switching [1]. In the present study, thin films of κ-Al2O3-type (A,Fe)2O3 (A =Al, Ga, Fe, Rh, Sc, and In) were prepared and their crystal structures, domain structures, ferroelectric and magnetic properties were systematically investigated experimentally and theoretically. Ferroelectricity was confirmed for all the films; however, the magnitude was found to be 10 ~ 20 % of the theoretical values [1], being correlated with the domain structures. Detailed polarization switching behavior and magnitudes of Ps, Pr, Ms, and TN for (A,Fe)2O3 will be discussed in the presentation.
[1] A. Konishi et al., unpublished