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
課題番号 Project No.

提出日 Date of Report
27th May 2016
装置責任者 Name of responsible person

2015A0225
実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Unconventional magnetic behavior in new diamond chain system

BL 12 (HRC)

K3Cu3AlO2(SO4)4

実施日 Date of Experiment
11/6-9 2015

実験責任者名 Name of principal investigator
Setsuo Mitsuda
所属 Affiliation
Tokyo University of Science
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.

K3Cu3AlO2(SO4)4

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.

Recently we have newly synthesized one-dimensional S=1/2 scalene diamond chain,
Alumoklyuchevskite K3Cu3AlO2(SO4)4 and succeeded in preparing pure-phase [1][M. Fujihala etal. J. Phys. Soc. Jpn. 84 073702(2015)]. As two broad characteristic peaks is seen at THM ~ 200K
and TLM ~50K in the magnetic susceptibility (see Fig.1), the magnetic short-range order develops
in a two-stage process, suggesting alternating dimers-monomer state (S=1/2 monomers are
separated by S=0 dimers on the diamond chain backbone) which has been inferred in the firstrealization of the distorted diamond chain system, Azurite, Cu3(CO3)2(OH)2 [2][H. Kikuchi et al.,Phys. Rev. Lett. 94, 227201 (2005)]. While Azurite shows a three dimensional long-range
magnetic ordering at 1.8 K, Alumoklyuchevskite dose not down to 0.5 K, indicating its very good
one-dimensionality. Therefore, to investigate if alternating dimers-monomer state is also realized
and what is the ground state of distorted diamond chain system, we performed inelastic neutron
scattering experiments on powder sample of Alumoklyuchevskite at 4 K and 100 K, where theenergies of the incident neutron were Ei = 205.8 meV and 45.95 meV (second frame) yielding anenergy resolutions of ΔE = 5 and 1 meV at the elastic position.

12. 実験方法及び結果（つづき） Experimental method and results (continued)
According to tentative analysis of magnetic susceptibility based on DMRG method, system can becomposed of antiferromagnetic S=1/2 chain with coupling constant of 75K and isolated dimers
with coupling constant of 450K, approximately. Therefore, inelastic neutron spectrum should becomposed of spinon excitation due to 1D AF S=1/2 Heisenberg chain and dispersionless excitation
due to isolated dimers.
In Fig.2 (a), the data of Ei = 45 meV, definite excitation starting from the zone center of Q = 0.68(Å-1) can be seen. Because of powder averaging of the dispersion relation, however, it is hard toidentify the spectrum as spinon excitation, as is seen in the inelastic neutron scattering data of apowder CuGeO3 in Fig.2 (c) [3][K.Tomiyasu et al., Appl. Phys. Lett.94, 092502 (2009)]. Definitely,
conversion method[3] of powder inelastic scattering data for one-dimensional systems is necessary
and data analysis using this method is now in progress.

In Fig.2 (b), a data of Ei = 200 meV,weakly dispersive excitation can be seen around 40 meV corresponding to coupling constant 450K
of isolated dimer. These results were consistent with an alternating dimer monomer spin liquid
model of the distorted diamond chain system.

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