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 Report2013. 2. 11

課題番号 Project No.

装置責任者 Name of responsible person

2012A0149

Yasuhiro Miyake

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）SR study of the magnetism and superconductivity in theD1

multi-layer Bi-2223 high-Tc superconductor

実施日 Date of Experiment

実験責任者名 Name of principal investigator2012. 10. 26-29

Tadashi Adachi
所属 Affiliation
Department of Applied Physics, Graduate School of Engineering,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.

Bi-based high-Tc superconducting cuprates
Bi2Sr2Ca 2Cu3O10+
Single crystals

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.

Zero-field (ZF) SR measurements have been performed at temperatures between ~ 7 K and 300 K in theunderedoped (Tc = 86.5 K) and optimally doped (Tc = 108.5 K) Bi2Sr2Ca2Cu3O10+ crystals.

Measurements

around the base temperature have been performed in the single-pulsed mode, while others have been performedin the double-pulse mode.
Because of thin crystals of Bi2Sr2Ca2Cu3O10+ with the thickness of ~ 0.1 mm, at first we performed ZF
measurements using Ho by changing the thickness of Ag foils as the degrader at the room temperature.
Through monitoring the strong depolarization of Ho, we finally decided the appropriate thickness of Ag foils tobe 150 m.
Figure 1 shows ZF-SR time spectra of the underdoped and optimally doped crystals.
data is a little low due to small surface of the crystal.

The statistics of theIt is found that in the underdoped crystal, the spectrum

depola12. 実験方法及び結果（つづき） Experimental method and results (continued)
show Gaussian-like slow depolarization at 211 K due to the randomly oriented nuclear spins. Below 211 K, thedepolarization of muon spins becomes fast down to 123 K. However, the spectrum does not change between
123 K and 32 K. The depolarization of muon spins becomes fast again below 32 K. These results suggest thatthe development of the Cu-spin correlation is not monotonic and two kinds of development of the Cu-spincorrelation exist.
For the optimally doped crystal, the spectra show Gaussian-like depolarization above 40 K, indicating theCu-spin fluctuations faster than the SR time window.

Below 40 K, a fast depolarization of muon spins isobserved. It is found that the development of the Cu-spin correlation is monotonic, which is different from thatin the underdoped crystals.
These contrasting results between the underdoped and optimally doped crystals suggest the followings. In
the underdoped crystals, the Cu-spin correlation in the inner CuO2 plane starts to develop below 211 K due to thelow hole concentration, while the Cu-spin correlation in the outer CuO2 plane starts to develop below 32 K due
to the high hole concentration. On the other hand, in the optimally doped crystals, the Cu-spin correlation in
the inner plane starts to develop below 40 K due to high hole concentration and no development of the Cu-spincorrelation is observed in the outer plane due to over doping of holes. To our knowledge, this is a firstobservation of the two kinds of the developed Cu-spin correlation in the multi-layer cuprates from SR. To beconclusive, SR measurements at lower temperatures are important.

Bi Sr Ca2Cu O
22

310+

Underdoped(Tc = 86.5 K)

1.0
0.8
0.6
0.4
T = 211 K
123 K
32 K
11 K
8.1 K

0.2

Bi Sr Ca2Cu O

1.2

Normalized Asymmetry

Normalized Asymmetry

1.223

T = 202 K
142 K
101 K
72 K
40 K
14 K
7.9 K

ZF10+

1.0

Optimallydoped(Tc = 108.5 K)

0.8
0.6
0.4
0.2

ZF

0200

51015

Time (sec)

0510

Time (sec)

Fig. 1. Zero-field SR time spectra of the underdoped and optimally doped Bi2Sr2Ca2Cu3O10+.

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