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.

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

2016B0239

Ishigaki, Toru

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Magnetic Structure of Ru2O9 dimer in Ba3Co1-xMxRu2O9 (M=Zn,iMATERIA (BL 20)

Ca)

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2017/2/1 ～ 2017/2/5

Yasui, Yukio

2017/3/21

所属 Affiliation
Meiji 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.

Ba3Co1-xCaxRu2O9 (x=0, 0.1, 0.2, 0.3)
LaAl1-xZnxO3 (x=0, 0.01, 0.02)

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.

We investigated the crystal structure and the magnetic structure of Ba3Co1-xCaxRu2O9 (x=0, 0.1, 0.2 and 0.3)

from 3.6K to 150 K particularly focusing on how the magnetic moment on Ru5+ begins to fluctuate with x.
The compounds with the general formula Ba3MRu2O9 (M=Co, Ca, Zn) have a hexagonal barium titanate
structure type, where the structure consists of units of two face-shared RuO6 octahedra (Ru2O9 dimers)
interconnected by perovskite-type corner sharing with MO6 octahedra. Ba3CoRu2O9 exhibits anantiferromagnetic transition at TN=98K. The magnetic structure of Ba3CoRu2O9 is already reported by Ref.
1, where the Co2+ and Ru5+ spins in the ordered state have the ordered moments of 2.7 B and 1.5 B,respectively. Recently, we have discovered a novel type of quantum spin liquid in Ba3ZnRu2O9, where any
traces of the Curie tail or glassy behavior of magnetic susceptibility have not been detected down to 50 mK[2]. We have controlled the magnetic ground state from an antiferromagnetic order to the gapless spin liquidstate by making a solid solution between Zn2+ and Co2+. The magnetic behavior of Ba3CaRu2O9 is also
investigated already by Ref. 3, and the spin system is in the nonmagnetic singlet state with the Ru5+ dimers.
12. 実験方法及び結果（つづき） Experimental method and results (continued)

We have also controlled the magnetic ground state from an antiferromagnetic order to nonmagnetic state bymaking a solid solution system Ba3Co1-xCaxRu2O9. With increasing the Ca-concentration, theantiferromagnetic transition temperature TN decreases such as TN=88K (x=0.1), 82K (x=0.2), and 76K (x=0.3),
respectively. We investigated the crystal structure and the magnetic structure of Ba3Co1-xCaxRu2O9 (x=0, 0.1,0.2 and 0.3) by the neutron powder diffraction measurements using the iMATERIA at MLF.
Figure 1 shows examples of neutron diffraction profiles of Ba3CoRu2O9 taken at various temperatures. We cansee the growth of intensities of the magnetic reflections, which is indicated by arrows. As a result of preliminary
magnetic structure analysis, the obtained results are almost similar to that of the repoted structure by ref. 1,
which is collinear magnetic structure of both Co2+ and Ru5+ spins along b-crystal axis. However, we observed
010 magnetic reflection, which can not be explained by the repoted structure. Then, the magnetic structure ofBa3CoRu2O9 seems to be canted structure from the reported collinear one. We are going to continue analyzing
neutron diffraction data.

Ba3CoRu2O9

1

Figure 2 shows the neutron diffraction

3.6K
40K
70K
80K
90K
100K
110K

profiles of Ba3Co1-xCaxRu2O9 with x=0,
Fig.2,

arrowsshow

themagneticreflections, and we can see the sharp
magnetic peak even in x=0.3. The

Intensity

0.1, 0.2, and 0.3 taken at T=3.6K. In

0.5intensities of several magnetic peaks
decrease with increasing x. On theother hand, the intensities of remaining

2peaks do not change by Ca-doping.

46d (Å)
Fig. 1: Profiles of the neutron diffraction of Ba3CoRu2O9 taken
at various temperatures. Arrows indicate the magneticreflections.

Then, the change of the magnetic
structure by Ca-substitution for Co isnot simple. We are going to carry out theBa3Co1–xCaxRu2O9

magnetic structure analysis. Moreover,

the results of the crystal structure
analysis of obtained data give us theT=3.6Kx=0x=0.1
x=0.2
x=0.30.6

the origin of different magnetic groundstates

between

Ba3CoRu2O9andBa3CaRu2O9.
[1] Lightfoot and D. Battle: J. SolidIntensity

important information to understand0.40.2

State Chem.89 (1990) 174.
[2] I. Terasaki et al.: J. Phys. Soc. Jpn.
86 (2017) 033702.
[3] M. Senn et al.: J. Phys.: Condens
Matter 25 (2013) 496008.

345d (Å)
Fig. 2: Profiles of the neutron diffraction ofBa3Co1-xCaxRu2O9 with x=0, 0.1, 0.2, and 0.3 samples taken
at T=3.6K. Arrows indicate the magnetic reflections..

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