Fig. 4: Spatial distribution of ferroaxial domains obtained via electrogyration in NiTiO3. | Nature Communications

Fig. 4: Spatial distribution of ferroaxial domains obtained via electrogyration in NiTiO3.

From: Visualization of ferroaxial domains in an order-disorder type ferroaxial crystal

Fig. 4

a Experimental setup of electrogyration measurement using a difference image-sensing technique. Inset of (a) shows temporal evolution of applied voltage V during the measurement. Microscopy images of transmitted light were captured by the area sensor while the positive and the negative V applied. The difference of transmittance between the positive- and negative-voltage images (ΔT) divided by the average of them (T) was calculated for each pixel detection, and then spatial distributions of ΔT/T were obtained. b Transmission optical microscopy image with the incidence of light along the c axis (Scale bar: 100 μm). Dark areas in the image correspond to NiO impurity. c, d The two-dimensional maps of ΔT/T, which corresponds to electrogyration, at the same area as panel b. A 3 × 3 median filter was applied to the raw images. The polarization direction of the analyzer was set at (c) θ = +45° and (d) −45° with respect to that of the polarizer. These measurements were done under V = ±100 V at room temperature, that is, in the R\(\bar 3\) ferroaxial phase. A ΔT/T color scale is applied to the images in panels c and d. Red and blue regions correspond to either A+ or A− ferroaxial domains. Purple-colored regions represent areas of NiO impurity.

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