常磁性から強磁性への遍歴電子メタ磁性転移 : Laves相化合物を中心にして

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The itinerant-electron metamagnetic transitions are reviewed from fundamental and practical viewpoints, laying stress on the Laves phase compounds. The metamagnetic transition is closely correlated with the coefficients of the Landau expansion of the magnetic free energy, which depend on the band structure. Namely, the negative coefficient of the 4th order term is necessary for the metamagnetic transition. The concentration dependence of the Curie temperature and the magnetic moment for Lu(Co_<1-x>Ga_x)_2 and Lu(Co_<1-x>Al_x)_2 Laves phase compounds exhibit a drastic change in the vicinity of the critical concentration for the metamagnetic transition. The metamagnetic transition field H_c decreases with increasing x. At low temperatures, H_c is proportional to the square of temperature, and H_c has a linear relationship with the temperature of the maximum susceptibility T_<MAX>, in support of Yamada's theory which takes into consideration of spin fluctuations. The electronic specific heat coefficient γ is reduced by applying magnetic fields due to suppression spin fluctuations. The importance of homogenization by heat-treatments is emphasized in order to obtain reliable physical parameters. The metamagnetic transition is accompanied by a huge volume expansion as well as a giant magnetoresistance. Especially, the linear expansion △L/L of La(Fe_<0.88> Si_<0.12>)_<13> exceeds the linear magnetostriction of TbFe_2.
社団法人日本磁気学会の論文
1998-08-01

著者

深道和明
東北大学大学院工学研究科材料物性学固体物性工学分野

常磁性から強磁性への遍歴電子メタ磁性転移 : Laves相化合物を中心にして

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