Indirect Exchange Interactions in Orthorhombic Lanthanide Aluminates
D. Petrov and B. Angelov
University of Plovdiv, Dept. of Physical Chemistry, 24, Tsar Asen Str., 4000 Plovdiv, Bulgaria
Received: December 14, 2011; in final form: August 14, 2012
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Magnetic exchange interactions in orthorhombic lanthanide monoaluminates LnAlO3, Ln = Sm-Yb have been determined semiempirically within the Anderson model of exchange in insulators. The constants of magnetic exchange have been evaluated assuming indirect exchange between pairs of nearest Ln3+-Ln3+ ions via 4 fn → 4 fn - 1i5d excitation and ionic polarization. The transfer integrals have been approximated by two-centre overlap integrals between four-term analytical 4 fn radial wave functions of Ln3+ ions. The results have been compared with the available experimental Néel temperatures in the same compounds. It has been found that in most cases the indirect exchange interactions present substantial contributions to the energy of the antiferromagnetically ordered state in LnAlO3.
DOI: 10.12693/APhysPolA.122.737
PACS numbers: 75.30.Kz, 75.30.Et