1998 Fiscal Year Final Research Report Summary
Magnetic Properties and Structure of Icosahedral Cluster Alloys
| Project/Area Number |
08455287
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Tohoku University |
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Principal Investigator |
FUKAMICHI Kazuaki Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (00005969)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITA Asaya Tohoku University, Graduate School of Engineering JSPS Fellowship, 大学院・工学研究科, 特別研究員
MATSUBARA Eiichiro Kyoto University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (90173864)
WASEDA Yoshio Tohoku University, Institute for Advanced Materials Processing, Professor, 素材工学研究所, 教授 (00006058)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Icosahedral cluster alloy / Giant spontaneous volume magnetostriction / Thermal expansion anomaly / Curie temperature / Spin fluctuation / Metamagnetic transition / Antiferromagnetism |
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| Research Abstract |
Spin fluctuations, magnetovolume effects, metamagnetic transition, low temperature specific heat of 3d transition metal crystals and amorphous alloys composed of icosahedral clusters have been investigated. The main results are summarized as follows :
1) Magnetic phase diagram and spin fluctuations of La(Fe_xAI1_<-x>)_<13>
Magnetic phase diagram near the phase boundary between the antiferromagnetism and the ferromagnetism is very similar to the phase diagram predicted by the spin fluctuation theory proposed by Moriya-Usami.
2) Giant volume magnetostriction and the control of the Curie temperature of La(Fe_xSi1_<-x>)_<13>
After the metamagnetic transition just above the Curie temperature, a giant magnetovolume effect has been observed in La(Fe_xSi_<1-x>)_<13>. From the practical point of view, the control of the Curie temperature has been investigated and it has been confirmed that the addition of Co is effective.
3) Comparison between magnetic properties of La(Co_<1-x>Mn_x)_<13> in crystalline and amorphous states.
The concentration dependence of the magnetic moment in the amorphous state is different from that in the crystalline state. The concentration range where the icosahedral clusters are formed for the amorphous alloys is wider than that for the crystalline alloys.
4) Structures of La(Co_<1-x>TM_x)_<13> amorphous alloys.
Structural differences between La(Co_<1-x>Cr_x)_<13> and La(Co_<1-x>Mn_x)_<13> amorphous alloys have been investigated. it has been pointed out that the icosahedral clusters in the latter alloys are deformed. Such a difference is explained by the atomic size difference between Mn and Cr.
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