実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report
課題番号 Project No. 2009B0019

提出日 Date of Report
2010.4.13
装置責任者 Name of responsible person
Fujio Maekawa

実験課題名 Title of experiment High Magnetic Field Neutron

装置名 Name of Instrument/（BL No.）

Diffractions in Frustrated Multi-ferroics

BL10

実験責任者名 Name of principal investigator

H. Nojiri

実施日 Date of Experiment

所属 Affiliation

2010.1.23.10:00-2010.1.26.10:00

Institute for Materials Research, Tohoku University
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
MnWO4 single crystal
CuFeO2 single crystal
NaCl single crystal

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

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

The purpose of our experiment is to conduct neutron diffraction in very high magnetic field above
40 T and to investigate the mechanism of multi-ferroic compounds.
In the previous proposal: 2009A0027, we have made the first application of pulsed magnetic field up
to 35 T. Considering the weak beam intensity of 20 kW, we have made a very simple measurements
on single crystals such as NaCl and CuFeO2 to examine the system performance. With a NaCl single
crystal of 0.7 cm3, a TOF spectrum is obtained by accumulating 134 shots over 22 hours in thepulsed magnetic field of 35 T. We have compared the [400] nuclear Bragg peak taken at 35 T withthat at zero field and found no clear difference. It means that the performance of the system ismaintained even in such high magnetic fields. It was the highest magnetic field for neutron
diffraction.
In the 2009B, the beam intensity has been around 100 kW, which is 5 times stronger. There are two
major achievements in the present run. (1) We have succeeded in the neutron diffraction up to 40 T
on the standard sample of NaCl. (2)We have examined the magnetic structure of multi-ferroic
compound BiFeO3.

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2. 実験方法及び結果（つづき） Experimental method and results (continued)

Fig. 1 Comparison of TOF spectrum in 40 T with zero fieldspectrum.

Fig. 2 Field pulse waveform for stretchedmode.

The former has established the neutron diffraction in very strong magnetic field. The latter has been
made as the first international proposal from J. G. Park group from Korea of our system, whichindicates the uniqueness of the system. The detail of the second part is given in the separate report.
Figure 1 shows the TOF spectrum of [400] nuclear Bragg peak of NaCl single crystal as thestandard. The proton beam power was 100 kW. There is no difference of TOF spectrum between 0and 40 T. It indicates that the performance of the system is maintained even in such high magnetic
fields. The number of the shots is 40 and it takes about 8 hours. The sufficient S/N ratio can beobtained in 20 shots and thus the diffraction at 40 T can be made in several hours with the beam
power of 100 kW. If we scale it to 500 kW, a few shots are enough for data accumulation. It meansthat much detailed experiments becomes possible. It demonstrates that neutron diffraction up to 40 T
has been established at J-PARC, which is very unique among neutron facilities.
Figure 2 shows the waveform of the stretched mode. In this case, the total pulse width can be as longas 20 msec. It is very useful to cover the different Brgg peak in one scan.
We have also examined other compounds such as MnWO4 and CuFeO2. Unfortunately, we could
not get a complete result for these compounds. A serious problem is that the sample check cannot bemade in advance because of the absence of the sample transport protocol from JRR3 and otherneutron facilities as a radio isotope.
In conclusion, in 2009B, we have established the 40 T neutron diffraction system by using pulsed
magnetic fields. The system is now ready for determination of the magnetic structure of various
compounds in high magnetic fields.

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