Theory of metal–insulator transition in PrFe4P12 and PrRu4P12
Theory of metal–insulator transition in PrFe4P12 and PrRu4P12
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PrFe4P12 和 PrRu4P12 金属-绝缘体转变理论
DOI：
10.1016/s0022-3697(02)00150-6
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发表时间：
2002
影响因子：
4
通讯作者：
K. Takegahara
中科院分区：
文献类型：
--
作者：
S. Curnoe;K. Ueda;H. Harima;K. Takegahara
我们推导出了PrFe_（4P）_（12）和PrRu_（4P）_（12）中Fe/Ru或P离子位移与Pr离子4f_2基态二重态之间的所有对称耦合。Fe/Ru位置的（1，1，−2）型畸变将4f 2二重态分裂成具有相反四极矩的非磁性本征态。畸变和四极矩的符号从一个位置到另一个位置交替，导致反四极有序。（1，1，1）型畸变并不能提高4f 2二重态的简并度。这两种畸变都可能在费米面打开一个能隙，导致PrRu 4P 12的金属-绝缘体转变和PrFe 4P 12的部分金属-绝缘体转变。
We derive all symmetry allowed couplings between Fe/Ru or P ion displacements and the Pr ion 4f2ground state doublet in PrFe4P12and PrRu4P12. A (1,1,−2)-type distortion of the Fe/Ru positions splits the 4f2doublet into non-magnetic eigenstates with opposite quadrupole moments. The sign of both the distortion and the quadrupole moment alternate from site to site, resulting in anti-quadrupolar ordering. A (1,1,1)-type distortion does not lift the degeneracy of the 4f2doublet. Either distortion may also open a gap at the Fermi surface, causing a metal–insulator transition in PrRu4P12and a partial metal–insulator transition in PrFe4P12.