Theory of Metal-Insulator Transition in Praseodymium Skutterudite Compounds
Theory of Metal-Insulator Transition in Praseodymium Skutterudite Compounds
复制标题
镨方钴矿化合物金属-绝缘体转变理论
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
K. Ueda
中科院分区：
文献类型：
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作者：
H. Harima;K. Takegahara;S. Curnoe;K. Ueda
对PrRu4P12的金属绝缘体相变和PrFe4P12的非磁性相变进行了理论研究。当Q=(1，0，0)时，费米面的嵌套性通过Fe/Ru位移与相变处的反四极有序相耦合。Fe/Ru离子与Pr4F2基态双重态的位移声子模之间的耦合导致了Fe/Ru位置的对称性降低(1，1，-2)型扭曲和4f2双重态同时分裂成具有四极矩±8的本征态。扭曲和四极矩的符号在不同位置交替，导致反四极有序。这两种化合物之间的差异源于PrFe4P12的另一个小费米表面，即使考虑嵌套效应，该带的存在也会抑制PrFe4P12的金属-绝缘体转变。因此，PrFe4P12的低温状态有望保持为金属状态.
The metal–insulator transition of PrRu 4 P 12 and the non-magnetic phase transition of PrFe 4 P 12 are theoretically investigated. The nesting property of the Fermi surface with q =(1,0,0) is coupled, through Fe/Ru displacements, with anti-quadrupolar ordering at the phase transitions. Coupling between phonon modes of the displacements of the Fe/Ru ions and the Pr 4 f 2 ground state doublet leads to a symmetry lowering (1,1,-2) type distortion of the Fe/Ru positions and a simultaneous splitting of the 4 f 2 doublet into eigenstates with quadrupole moments ±8. The sign of both the distortion and the quadrupole moment alternate from site to site, resulting in anti-quadrupolar ordering. The difference between these two compounds stems from another small Fermi surface in PrFe 4 P 12 ; the presence of this band would suppress the metal-insulator transition in PrFe 4 P 12 , even after the nesting effect is taken into account. Therefore, the low temperature state of PrFe 4 P 12 is expected to remain metallic.