Rare case of magnetic Ag${}^{3+}$ ion: double perovskite Cs${}_2$KAgF${}_6$

Abstract

Normally $4d$ or $5d$ transition metals are in a low-spin state. Here using first-principles calculations, we report on a rare case of a high-spin $S$=1 magnetic state for the Ag${}^{3+}$ ion in the double perovskite Cs${}_2$KAgF${}_6$. We also explored a possibility of a conventional low-spin $S$=0 ground state and find an associated tetragonal distortion to be 0.29 Å. However, the lattice elastic energy cost and the Hund exchange loss exceed the e${}_g$ crystal-field energy gain, thus making the low-spin tetragonal structure less favorable than the high-spin cubic structure. We conclude that the compact perovskite structure of Cs${}_2$KAgF${}_6$ is an important factor in stabilizing the unusual high-spin ground state of Ag${}^{3+}$.

6 pages, 6 figures, accepted for publication in PRB

References in corpus (6)

• Spin blockade, orbital occupation and charge ordering in La_(1.5)Sr_(0.5)CoO4
• Spin state transition and covalent bonding in LaCoO3
• Orbitally driven spin-singlet dimerization in $S$=1 La${}_4$Ru${}_2$O${}_{10}$
• Importance of exchange-anisotropy and superexchange for the spin-state transitions in LnCoO3 (Ln=La,Y,RE) cobaltates
• Ab initio study of the giant ferroelectric distortion and pressure induced spin-state transition in BiCoO3
• Orbital ordering in the ferromagnetic insulator Cs${}_2$AgF${}_4$ from first principles

Cited by in corpus (1)

• Analysis of charge states in the mixed valent ionic insulator AgO