FERROMAGNETIC COUPLING IN NONMETALLIC CU2+ COMPOUNDS

被引：36

作者：

FELDKEMPER, S ^{[1
]}

WEBER, W ^{[1
]}

SCHULENBURG, J ^{[1
]}

RICHTER, J ^{[1
]}

机构：

[1] UNIV MAGDEBURG,INST THEORET PHYS,MAGDEBURG,GERMANY

来源：

PHYSICAL REVIEW B | 1995年 / 52卷 / 01期

关键词：

D O I：

10.1103/PhysRevB.52.313

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Analytical and numerical studies of ferromagnetic coupling in nonmetallic Cu2+ compounds are presented. In addition to the well-known Goodenough-Kanamori- Anderson (GKA) mechanism, further possibilities for ferromagnetic interactions in insulators are investigated, using the concept of interference between inequivalent superexchange paths. The basic idea is discussed by considering Hubbard-type Hamiltonians for a simple four-site cluster with two magnetic ions and two inequivalent ligands. Here, destructive interference of hopping paths may completely suppress the antiferromagnetic coupling between the ground-state orbitals at the magnetic sites. Then, in a specific range of model parameters, ferromagnetic coupling is possible involving only ground-state orbitals. Using corresponding model Hamiltonians for realistic clusters, the range of ferromagnetic coupling in the nonmetallic ferromagnets K2CuF4 and La2BaCuO5 is investigated, both by perturbation theory and by exact diagonalization calculations. For the two compounds the in-plane coupling is ferromagnetic in accordance with the GKA rules. However, the ferromagnetic interplanar coupling is caused by interference effects. © 1995 The American Physical Society.

引用

页码：313 / 323

页数：11

共 47 条

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