Experimental Report
Project No.

Date of Approval 2017/05/17
Approver Kaoru Shibata
Date of Report 2017/05/11

Name of Instrument scientist

Title of experiment

Name of Instrument/ BL No.

Name of principal investigator

Date of Experiment

Affiliation

Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
Name of sample(s) and chemical formula, or compositions including physical form.

Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

In this proposal, we focused upon understanding the dynamics of the domain walls considered
to be contributing to the large susceptibility in the ferroelectrics. We have constructed a suitable
experimental system for studying the dynamics of the domain walls in the typical and well known
ferroelectrics BaTiO3, where BaTiO3 has no chemical heterogeneity and allows us to construct anideal experimental system. Concretely speaking, we have prepared two samples withandby the electric field application and search for the domain-wall

dynamics by the inelastic neutron scattering expected to appear in the quasielastic (micro-eV)
region by comparing the two samples.

Experimental method and results (continued)
Two single crystals of BaTiO3 with the dimension of 10 x 10 x 3 (x, y, z) mm3 were prepared.
One is <111> cut and the other is <001> cut perpendicular to the z-axis of the sample. The former
case, the application of the electric field of 10 kV/cm resulted in theconfiguration with a few micro meter domain size, while the latter case, the application of theelectric field resulted in the almost.

The sample was set in the Cryo-furnace installed at BL02/MLF and the temperature wascontrolled from room temperature (tetragonal and ferroelectric phase) to 420 K (cubic andparaelectric phase). The quasielastic scattering was measured near the 010 Bragg position. We
compared the quasi-elastic scattering spectra fromBaTiO3 andBaTiO3, and found a dynamics considered to be from the domain walls. Figure 1 shows thespectrum of the quasielastic scattering measured at (0.03, 1, 0) (red filled circle) as well as
resolution (green line). In the spectrum, two components can be observed; one is nearly resolution
limit (~3.5 micro eV) and the other (tail of the scattering) is broader than the resolution.

Fig. 1 Observed quasielastic scattering spectrum (red filled circle) from 111-cut BaTiO3
measured at (0.03, 1, 0). The observed resolution function (green) is also shown.
As previously reported [1], there are two dynamics related to the domain wall; low-frequency(~0.1 GHz) dispersion is related to the domain wall vibrations, while the high-frequency (~10 GHz)
dispersion is attributed to the flip of individual dipoles. The observed dynamics nearly resolution
limit is considered to be the domain wall vibrations, while the dynamics broader than theresolution is considered to be the flip of individual dipoles. These peaks almost disappeared at 420
K indicating that the spectrum was originated from the ferroelectric phase. More detailed analysis
is now under processing.
[1] P. Chu, Scientific Report 05007 (2014).