Giant exchange interaction in mixed lanthanides

Abstract

Combining strong magnetic anisotropy with strong exchange interaction is a long standing goal in the design of quantum magnets. The lanthanide complexes, while exhibiting a very strong ionic anisotropy, usually display a weak exchange coupling, amounting to only a few wavenumbers. Recently, an isostructural series of mixed Ln${}^{3+}$-N${}_2^{3-}$-Ln${}^{3+}$ (Ln $=$ Gd, Tb, Dy, Ho, Er) have been reported, in which the exchange splitting is estimated to reach hundreds wavenumbers. The microscopic mechanism governing the unusual exchange interaction in these compounds is revealed here by combining detailed modeling with density-functional theory and {\it ab initio} calculations. We find it to be basically kinetic and highly complex, involving non-negligible contributions up to seventh power of total angular momentum of each lanthanide site. The performed analysis also elucidates the origin of magnetization blocking in these compounds. Contrary to general expectations the latter is not always favored by strong exchange interaction.

15 pages, 5 figures, 11 tables. With minor revision

References in corpus (4)

• Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
• Exchange interaction between $J$-multiplets
• Thermodynamics of anisotropic triangular magnets with ferro- and antiferromagnetic exchange
• Ising exchange interaction in lanthanides and actinides

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• Multipolar exchange interaction and complex order in insulating lanthanides
• Lanthanide-radical magnetic coupling in [LnPc${}_2$]${}^0$: Competing exchange mechanisms captured via ab initio multi-reference calculations
• Importance of Dispersion and Relativistic Effects for ORR Overpotential Calculation on Pt(111) surface