実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
2012/07/27

課題番号 Project No.

装置責任者 Name of responsible person

2012A0128

Yasuhiro Miyake

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Development of high pressure cell for muon spin rotation andrelaxation experiments at JPARC/MUSE and its application to organic
systems

D1

実験責任者名 Name of principal investigator2012/05/11～2012/05/13

実施日 Date of Experiment

Kazuhiko Satoh所属 Affiliation
Graduate School of Science and Engineering, Saitama 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.
NiCrAlDaphne oil 7474
Teflon2. 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.

Ground states of strongly correlated electron systems are very sensitive to external conditions. Especially,
application of high pressure is an important technique because some of strongly correlated electron systems arelocated near the quantum critical point and exotic phenomena, e. g. non-Fermi liquid behavior and/orpressure-induced superconductivity, are frequently seen around the quantum critical point.
Muon spin rotation and relaxation method is an important technique to investigate microscopic magnetic
properties for strongly correlated electron systems and we have continued to develop the high-pressure SR
technique at KEK and TRIUMF until now. Maximum muon momentum is about 100 MeV/c for KEK andTRIUMF, whereas it is about 70MeV/c for J-PARC MUSE D1 area. Thickness of a high pressure cell for
J-PARC should be smaller and maximum pressure will be limited as compared to previous cells. Nevertheless,ground state of strongly correlated systems is sensitive to external pressure and various interesting phenomena
are expected even below 1GPa. Therefore development of high pressure cell for J-PARC MUSE is valuable.
12. 実験方法及び結果（つづき） Experimental method and results (continued)
We have prepared a new high pressure cell using non-magnetic NiCrAl alloy for J-PARC/MUSE
D1 by changing the design. Maximum pressure is estimated to be 1 GPa at room temperature.
Using new pressure cells, we carried out following experiments.
1. SR study of NiCrAl alloy at ambient pressure
We first check the zero-field SR signal of high pressure cell itself, namely NiCrAl alloy, between 8
and 70 K at ambient pressure. SR spectra of NiCrAl alloy are described by Kubo-Toyabe-type
relaxation function and relaxation rate of NiCrAl is found to be smaller than that of previously
used material, MP35N. NiCrAl is suitable for high-pressure cell for SR.
2. New pressure medium Daphne 7474
Recently Murata et al. reported that a new pressure medium named Daphne 7474 shows
high-quality hydrostaticity. We carried out zero-field SR experiment for Daphne 7474 and foundthat SR spectra of Daphne 7474 show relaxation signals which are similar to those of previously
used Daphne 7373. Although Daphne 7474 is expensive, it is suitable for pressure medium for
SR,
3. Determination of optimum muon momentum for our pressure cellIn high pressure SR experiment, some of muons will stop at a pressure cell and it is important to determine
optimum muon momentum for individual pressure cells. We tried to determine optimum momentum bymeasuring asymmetry of Teflon as a function of muon momentum. We chose 75 and 80 MeV/c as muon
momentum. We could not distinguish the SR signal of Teflon, however, presumably due to the improper tuning
condition. We would like to continue high pressure SR experiments by improving the tuning condition.

2