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High Time Resolution μSR Study with Intense DC Muon Beam

使用强直流 μ 子束进行高时间分辨率 μSR 研究

基本信息

批准号：
11691135
负责人：
NISHIYAMA Kusuo
金额：
$ 3.9万
依托单位：
HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11691135/
关键词：
μSR DC-muon beam copper oxide heavy fermion cerium compounds pressure dependence low dimensionality hydrogen impurity in semiconductor 負ミュオン準位交差法負ミュオン移行反応

项目摘要

Various subjects in material science were studied at TRIUMF in Canada. The intense DC muon beam enables us a high time resolution μSR, which is beyond the capability with the pulsed muon beam at the unique muon facility in Japan (KEK-MSL). The following μSR experiments were performed. A novel superconducting material YNi_2B_2C was studied with transverse field μSR up to 5T.From the precise analysis of field distribution observed by muon in the mixed state (flux line lattice phase) of the single crystal sample, magnetic penetration depth λ and vortex core radius ρv was deduced. λ increases linearly with magnetic field. On the contrary ρv shrinks steeply with increasing field and subsequently levels off at higher field. Using a high quality single crystal CuO, coherent muon spin precession was observed at the intermediate magnetic phase (216K-232K) under zero field. In the antiferromagnetic ordered phase, the local internal magnetic fields were determined precisely, inclusively its tempe … More rature dependence and its orientations. High pressure μSR was performed on the CeRh_2Si_2 up to 0.6GPa. This sample is interesting because it shows a magnetic phase transition at 36K(T_N) under ambient pressure but T_N decreases with pressure and goes into a superconducting phase. To achieve higher pressure in μSR experiment more developments are necessary and are under way. From the Knight shift measurement in LiV_2O_4, which shows heavy fermion feature in spite of consisting from 3d-electrons, two unequivalent sites of V were found at ultra low temperature. Layered compounds Cu(OH)X were studied by μSR in its magnetic ordered state. The difference of magnetic structure was confirmed with the number of precession frequencies (two for X=Cl, Br, one for X=I). The proposal to achieve the repolarization of muonic atom in GaAs by laser optical pumping was accepted and experiments were performed but with no significant effect. Further improvement in the set up is needed. Ce compounds study using negative muon was started. μ^-SR signal in metallic cerium was successfully observed. Less

在加拿大的TRIUMF学习了材料科学的各种科目。强流直流μ子束使我们能够获得高时间分辨率的μSR，这超出了日本唯一的μ子装置（KEK-MSL）的脉冲μ子束的能力。进行以下μSR实验。研究了一种新型超导材料YNi_2B_2C，其横向磁场μSR可达5 T。通过对μ子在单晶样品混合态（磁通线晶格相）中观测到的磁场分布的精确分析，推导出了磁穿透深度λ和涡核半径ρv。λ随磁场线性增加。相反，ρv随场的增大而急剧收缩，随后在更高的场处趋于平稳。利用高质量的CuO单晶，在零场条件下观测到了中磁相（216 K-232 K）μ子自旋的相干旋进。在反铁磁有序相中，精确地确定了局部内磁场，包括其滕佩 ...更多信息特征依赖性及其取向。在0.6GPa的高压下对CeRh_2Si_2进行了μSR。该样品在常压下在36 K（T_N）发生了磁相变，但T_N随压力的增加而减小，并进入超导相。为了在μSR实验中实现更高的压力，更多的发展是必要的，并正在进行中。LiV_2O_4虽然由3d电子组成，但仍显示出重费米子的特征，从Knight位移测量中发现了V在超低温下的两个不等价位置。用μSR方法研究了层状化合物Cu（OH）X的磁有序态.用旋进频率的数目（X=Cl，Br时两个，X=I时一个）证实了磁性结构的差异。利用激光泵浦实现GaAs中μ子原子再极化的设想被接受，并进行了实验，但效果不明显。需要进一步改进设置。开始了利用负μ介子的Ce化合物研究。成功地观测到了金属铈中的μ^-SR信号。少