Stabilization of A-type layered antiferromagnetic phase in LaMnO3 by cooperative Jahn-Teller deformations

被引:23
作者
Capone, M
Feinberg, D
Grilli, M
机构
[1] Ist Nazl Fis Mat, I-34013 Trieste, Italy
[2] SISSA, ISAS, Int Sch Adv Studies, I-34013 Trieste, Italy
[3] Univ Grenoble 1, CNRS, Etud Proprietes Elect Solides Lab, F-38042 Grenoble 9, France
[4] Univ Roma La Sapienza, Ist Nazl Fis Mat, I-00185 Rome, Italy
[5] Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy
关键词
D O I
10.1007/s100510070164
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
It is shown that the layered antiferromagnetic order in stoechiometric LaMnO3 cannot be understood purely from electronic interactions. On the contrary, it mainly results from strong cooperative Jahn-Teller deformation. Those involve a compression of the Mn-O octahedron along the c-axis (mode Q(3) < 0), while alternate Jahn-Teller deformations occur in the ab-plane (mode Q(2)). These deformations stabilize a certain type of orbital ordering. The resulting superexchange couplings are calculated by exact diagonalization, taking into account both e(g) and t(2g) orbitals. The main result is that antiferromagnetic (ferromagnetic) coupling along the c-direction (ab-planes) can be understood only if the Jahn-Teller energy is much larger than the superexchange couplings, which is consistent with experiments. This mechanism contrasts with that based on weak Jahn-Teller coupling which instead predicts elongation along the c-axis (Q(3) > 0). The crucial role of the deformation anisotropy Q(2)/Q(3) is also emphasized.
引用
收藏
页码:103 / 109
页数:7
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