実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report

提出日 Date of Report
2017/12/13

課題番号 Project No.

装置責任者 Name of responsible person

2017A0030

Kenji Nakajima

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Magnetic excitations of chiral-lattice semiconductors Ce3T4Sn13

BL14 (AMATERAS)(T = Co, Ru, and Rh)

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2017/10/25 – 2017/11/1

Kazuaki Iwasa
所属 Affiliation
Ibaraki 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.
Ce3Ru4Sn13 polycrystalline sample (2 g)
La3Ru4Sn13 polycrystalline sample (2 g)

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 conducted an inelastic-neutron-scattering (INS) experiment of magnetic excitations of Ce3Ru4Sn13,
which has been reported to exhibit strongly correlated electron phenomena. According to the previous studies,
the specific-heat value divided by temperature of the isomorphic compounds Ce3Co4Sn13 [1-3] andCe3Rh4Sn13 [4-6] reach approximately 0.4 - 4 J/(mol-Ce K2) at 1 K, indicating formation of heavy electrons.
The electrical resistivity data of these Ce-based compounds are less dependent on temperature comparedwith that of the La-based superconductors. The resistivity data slightly increase with decreasing temperature
below 15 - 20 K and exhibits a maximum at 1 - 2 K. In contrast, no magnetic ordering was observed, despitethat the Curie-Weiss law for the Ce3+ 4f1 configuration reproduces well the magnetic susceptibility data. These
anomalous behaviors are likely due to hybridization between the Ce 4f and conduction electrons (c-fhybridization), which may cause low carrier concentration. In order to clarify the 4f-electron states in these
3-4-13 systems, we measured magnetic INS spectra of Ce3Ru4Sn13. We succeeded in observing characteristic
excitation spectra of the 4f electrons derived from difference in the spectra between Ce3Ru4Sn13 andLa3Ru4Sn13, which were synthesized using the molten Sn self-flux method.
2. 実験方法及び結果（つづき） Experimental method
1 and results (continued)

2. 実験方法及び結果（つづき） Experimental method and results (continued)
The polycrystalline samples of these two compounds with the same mass were sealed inside aluminum
containers with the same manner. This procedure assures us of extraction of the 4f-electron spectrum fromdirect subtraction of the data of the two compounds. The containers were installed in the 1-K 3He refrigerator.
We adopted the multi-Ei mode with the incident neutron energies, Ei = 3.43, 5.25, 8.98, 18.7, and 60.4 meV. The
pulse-shaping choppers were used in order to discuss the spectral shape.
Figure 1 shows an energy spectrum obtained with Ei = 60.4

0.004
Ei = 60.4 meV, T = 0.6 K
Ce3Ru4Sn13 (#1+#2)
Magnetic excitation

meV, the intensity of which is the sum in the Q = 3 – 5 Å-1 region.
observed. This result is considerably different from the previous
results

showingthesharp

excitation

peaks

betweencrystalline-electric-field (CEF) splitting levels of the Ce3+0.003

Intensity (arb. unit)

A distinctly broad excitation peak located at 18 meV was0.002

0.001

0.000

4f-electron state at 6.4 and 29 meV for Ce3Co4Sn13 [7] (Proposal-20

Nos. 2014P0202 and 2013B0173) and those at 7 and 39 meV forCe3Rh4Sn13 [8] (Proposal No. 2016A0063). The present Ru-based
compound takes stronger hybridization effect between the 4f andconduction electrons. Figure 2 shows a spectra measured using

20304050

at 0.6 K using Ei = 60.4 meV.
0.030

0.020

Intensity (arb. unit)

spectrum, while the data at 0.6 K show an inelastic feature atforms spin excitation with respect to the doublet CEF ground

10Fig. 1 Measured magnetic INS spectrum

0.025

the low temperature indicates that the 4f electrons in Ce3Ru4Sn130E (meV)

Ei = 3.44 meV. The data sets at 20 K show quasielastic-likeapproximately 0.8 meV. This emergence of inelastic response at-10

Ei = 3.44 meV
Ce3Ru4Sn13 (#1+#2)
Magnetic excitation

0.6 K
20 K

0.015
0.010
0.005

state. The similar spin excitations were also observed in the0.000

isomorphic compound Ce3Co4Sn13 and Ce3Rh4Sn13, which emerge-2-1

012E (meV)with the upturn in electrical resistivity below 15 K. However, theFig.

peak position and the spectral width of Ce3Ru4Sn13 are larger thanspectrum at 0.6 and 20 K using Ei =those observed for Ce3Co4Sn13 and Ce3Rh4Sn13. Therefore, an

3.44 meV.

2

MeasuredmagneticINS

energy scale of the spin correlation is enhanced for Ce3Ru4Sn13.
We found that the crystal structure of Ce3Co4Sn13 below 160 K and that of Ce3Rh4Sn13 below 250 K arecharacterized by chiral symmetry [9, 10]. This structural finding supports that the electrons in thesecompounds are the Wyle fermions [11]. The enhancements in the c-f hybridization and the spin correlation of
Ce3Ru4Sn13 are also interested in terms of electronic states characteristic of the chiral-lattice system.
Therefore, the structural investigation is required for understanding the electronic and magnetic properties.
References [1] A. L. Cornelius et al.: Physica B 378–380 (2006) 113. [2] A. Ślebarski et al.: PRB 86 (2012)
205113. [3] E. L. Thomas et al.: J. Solid State Chem. 179 (2006) 1642. [4] U. Köhler et al., J. Phys.: Condens.
Matter 19, 386207 (2007). [5] M. Gamża et al., J. Phys.: Condens. Matter 20, 395208 (2008). [6] A. Ślebarski etal., PRB 86, 205113 (2012). [7] K. Iwasa et al., PRB 95, 195156 (2017). [8] K. Iwasa et al., in preparation. [9] Y.
Otomo et al., PRB, 075109 (2016). [10] K. Suyama et al., in preparation. [11] J. L. Mañes, PRB 85, 155118(2012).
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