Meta-magnetism in Uranium-base Ferromagnetic Superconductors by Magnetic Compton Scattering

磁康普顿散射在铀基铁磁超导体中的超磁性

基本信息

批准号：
15540356
负责人：
SAKURAI Yoshiharu
金额：
$ 1.79万
依托单位：
Japan Synchrotron Radiation Research Institute
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Coexistence of ferromagnetism with superconductivity in UGe_2 has drawn much attention form many research scientists. The meta-magnetism observed in the ferromagnetic phase has been intensively studied in connection with the mechanism of the superconductivity. The aim of this project is to understand the meta-magnetism in an atomic-scale level by using the magnetic Compton scattering technique.We have carried out magnetic Compton scattering experiments on ferromagnetic UGe_2 at ambient pressure and have not find any anomalies in spin moment across the meta-magnetic transition temperature of 32 K. By combining with the magnetization data available in literatures, we have successfully separated the spin and orbital moments. The ratio of orbital moment to spin moment (L/S) is determined to be almost constanat, L/S=-0.2〜-2.3,over the temperature range between 10 K and 60 K. In the line-shape of magnetic Compton scattering (magnetic Compton profile), however, we have found significant changes across the meta-magnetic transition.In order to explain the origin of the changes observed in magnetic Compton profiles, we have fit atomic profiles of U-5f orbitals with different magnetic quantum number (m). The value of L/S predicted by the present fit is in good agreement with the above-mentioned, experimental values, showing the validity of the present model fitting.The fitting results show that the observed changes in the magnetic Compton profiles are caused by the changes of the weight of the m=1 and m=2 orbital states, suggesting strong fluctuation in the hybridization with Ge p states.In addition, we have performed high-pressure measurements at 1.0 GPa. The data-processing is in progress.

UGe_2中铁磁性与超导性的共存引起了许多研究科学家的关注，人们对铁磁相中观察到的超磁性与超导机制进行了深入研究。该项目的目的是了解超磁性。利用磁康普顿散射技术在原子尺度上进行了磁康普顿散射实验。我们对铁磁UGe_2进行了磁康普顿散射实验在环境压力下，在32 K的变磁转变温度范围内没有发现任何自旋矩的异常。通过结合文献中可用的磁化数据，我们成功地分离了自旋矩和轨道矩与自旋的比值。确定磁矩（L/S）在10 K到60 K的温度范围内几乎恒定，L/S=-0.2〜-2.3。在磁康普顿散射的线形中（磁康普顿剖面），然而，我们发现了亚磁性转变过程中的显着变化。为了解释磁康普顿剖面中观察到的变化的起源，我们拟合了具有不同磁量子数的U-5f轨道的原子剖面(m) 本拟合预测的L/S值与上述实验值吻合较好，表明本模型拟合的有效性。拟合结果表明观察到的磁康普顿剖面的变化。是由以下变化引起的m=1 和 m=2 轨道态的权重，表明与 Ge p 态杂化的强烈波动。此外，我们已经在 1.0 GPa 下进行了高压测量，数据处理正在进行中。