Negative mode-mode coupling among spin fluctuations and the magneto-volume effect in an itinerant-electron ferromagnet
Negative mode-mode coupling among spin fluctuations and the magneto-volume effect in an itinerant-electron ferromagnet
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流动电子铁磁体中自旋涨落与磁体积效应之间的负模-模耦合
DOI：
10.1088/0953-8984/6/49/021
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
K. Terao
中科院分区：
文献类型：
--
作者：
H. Yamada;K. Terao
利用朗道-金兹伯格能量展开到磁化强度的六次方，讨论了自旋涨落之间存在负模-模耦合的巡游电子铁磁体的自发体积磁致伸缩和居里温度Tc对压力P的依赖关系.根据朗道系数的大小，发现自发磁矩在Tc处呈现一级和二级跃迁。结果表明，当朗道系数满足一定的条件时，T=0时的自发体积磁致伸缩与T_c的差异很大，T_c的P依赖性也变得非常大。本理论的结果可以解释在因瓦合金、某些Laves相Co化合物和其他化合物中观察到的热膨胀的反常T依赖性和Tc的强P依赖性。
By making use of the Landau-Ginzburg energy expanded up to the sixth power of magnetization density, the spontaneous volume magnetostriction and dependence on pressure P of the Curie temperature Tc of an itinerant-electron ferromagnet with negative mode-mode coupling among spin fluctuations are discussed. The spontaneous moment is found to show first-order and second-order transitions at Tc, according to the values of the Landau coefficients. It is shown that the difference between the spontaneous volume magnetostrictions at T=0 and Tc is large and the P-dependence of Tc becomes anomalously large when a certain condition is satisfied by the Landau coefficients. The results obtained in the present theory could explain the anomalous T-dependence of the thermal expansion and the strong P-dependence of Tc observed in Invar alloys, some Laves phase Co compounds and others.