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GIANT SPIN FLUCTUATIONS IN LAVES PHASE YMn_2

LAVES 相 YMn_2 中的巨大自旋波动

基本信息

批准号：
62540238
负责人：
SHIGA Masayuki
金额：
$ 1.22万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62540238/
关键词：
Laves phase YMn_2 Spin fluctuations Electronic specific heat Electric resistivity Heavy Fermion Spin glasses Frustration ラーベス相スピンの揺ぎ近藤効果 YMn2 重いフェルミ粒子系中性子散乱

项目摘要

By substituting Sc for Y, an itinerant antiferromagnt YMn_2 becomes a Pauli paramagnet. We have shown by thermal expansion analysis and neutron scattering, experiments that giant spin fluctuations are thermally excited. In this research, we have measured the low temperature specific heart, electric resistivity and have shown that this system has characteristics of heavy Fermion systems although it contains neither 4f nor 5f element. In addition, we have investigated the magnetism and other properties of Y(Sc)(Mn_<1-x>Al_x)_2 system and have shown that anomalous properties of the present system may originate in frustrative magnetic interactions. Main results for each year are given below:1987(1) The low temperature specific heat of Y_<0.95>Sc_<0.05>Mn_2 was measured. It has been revealed that the electronic specific heat coefficient of this material is the largest in 3d metallic systems as gamma=145mJ/mol・K^2. (2) The temperature dependence of electrical resistivity was measured for Y_<0.95>Sc_<0.05>Mn_2 from 4.2K to 300K. We have shown that the coefficient of T^2 term is very large as A=0.25mu OMEGA cm/K^2,which is comparable to that of heavy Fermion systems.1988(1) The system for low temperature specific heat measurements was automated by using a micro-computer. Using this system, the low temperature specific heats of Y_<1-x>Sc_xMn_2 were measured and the gamma value was obtained as a function of concentration. The system for low temperature specific heat measurements was automated by using (2) The electric resistivity of Y_<0.95>Sc_<0.05>(Mn_<1-x>Al_x)_2 was measured as a function of temperature and revealed that the system transfers from a heavy Fermion like to a local moment system.1989Magnetic susceptibility and low temperature specific heat of Y_<0.95>Sc_<0.05>(Mn_<1-x>Al_x)_2 system were measured. We explained the characteristic properties of these systems as a result of magnetic frustrations.

通过用Sc取代Y，巡回反铁磁体YMn_2成为泡利顺磁体。我们已经通过热膨胀分析和中子散射实验证明了巨大的自旋涨落是热激发的。在本研究中，我们测量了低温比心电阻率，结果表明，该系统虽然不含4f和5f元素，但仍具有重费米子系统的特点。此外，我们还研究了Y(Sc)(Mn_&lt；1-x&gt；Al_x)_2体系的磁性和其他性质，结果表明，本体系的反常性质可能起源于受阻的磁相互作用。各年的主要结果如下：1987(1)测量了Y&lt；0.95&gt；Sc&lt；0.05&gt；Mn2的低温比热。结果表明，在三维金属系统中，该材料的电子比热系数最大，伽马=145mJ/mol·K^2。(2)从4.2K到300K测量了Y_&lt；0.95&gt；Sc_&lt；0.05&gt；Mn_2的电阻率与温度的关系。结果表明，T^2项的系数很大，为A=0.25µomega cm/K^2，可与重费米子系统的T^2系数相媲美。1988(1)低温比热测量系统用微型计算机实现了自动化。利用该系统测量了Y&lt；1-x&Gt；Sc_xMn2的低温比热，得到了随浓度变化的伽马值。利用(2)测量了Y_&lt；0.95&gt；Sc_&lt；0.05&gt；(Mn_&lt；1-x&gt；Al_x)_2的电阻率随温度的变化关系，发现该系统从重费米子系统向局部矩系统转变。对Al_x)_2体系进行了测量。我们解释了这些系统由于磁阻而产生的特征性质。