Frustrated Antiferromagnetic Spin Chains of Edge-Sharing Tetrahedra in Volcanic Minerals K3Cu3(Fe0.82Al0.18)O2(SO4)4 and K4Cu4O2(SO4)4MeCl

Abstract

The calculation of the sign and strength of magnetic interactions in two noncentrosymmetric minerals (klyuchevskite, K3Cu3(Fe0.82Al0.18)O2(SO4)4 and piipite, K4Cu4O2(SO4)4Cu0.5Cl) has been performed based on the structural data. As seen from the calculation results, both minerals comprise quasi-one-dimensional frustrated antiferromagnets. They contain frustrated spin chains from edge-sharing Cu4 tetrahedra with strong antiferromagnetic couplings within chains and very weak ones between chains. Strong frustration of magnetic interactions is combined with the presence of the electric polarization in tetrahedra chains in piipite. The uniqueness of magnetic structures of these minerals caused by peculiarities of their crystal structures has been discussed.Keywords: Frustrated quasi-one-dimensional antiferromagnets, tetrahedral spin chains, klyuchevskite K3Cu3(Fe0.82Al0.18)O2(SO4)4, piypite K4Cu4O2(SO4)4MeCl.

Spin-frustrated pyrochlore chains in the volcanic mineral kamchatkite (KCu3OCl(SO4)2)

“…Oxocentered copper OCu 4 tetrahedra forming the basis the crystal structure serve as a platform for geometric frustration of the magnetic system of not only kamchatkite, but also many minerals of Kamchatka Tolbachik volcanos. As we demonstrated in [Volkova and Marinin, 2017], the uniqueness of these systems consisted in the fact that the antiferromagnetic character of couplings along the tetrahedron edges and, therefore, frustration of exchange interactions on triangular faces were caused mainly by oxygen ions centering copper tetrahedra. This oxygen ion is an intermediate one simultaneously in all six couplings along the tetrahedron edges and makes a substantial contribution to formation of the AFM character of these couplings.…”

Copper–lead selenite bromides: a new large family of compounds partly having Cu2+ substructures derivable from kagome nets

“…Oxocentered structural motifs with Cu 2+ vertices have recently been reported to be responsible for a number of unusual magnetic properties (Fujihala et al, 2017;Badrtdinov et al, 2018;Volkova & Marinin, 2017). Different kagome-netderived Cu 2+ substructures (Fig.…”

“…Provided that appropriate distances and suitable exchange pathways between the S = 1 2 Cu 2+ cations, low temperatures and perhaps certain requirements for crystal purity are given, the tetrahedra and triangles observed in the structures of the second group allow for the occurrence of geometrically frustrated magnetic systems with a variety of unusual features, see e.g. Fujihala et al (2017), Volkova & Marinin (2017), Shores et al (2005). Corresponding experiments have not been performed yet and are beyond the scope of the present study.…”

Rb2CaCu6(PO4)4O2, a novel oxophosphate with a shchurovskyite-type topology: synthesis, structure, magnetic properties and crystal chemistry of rubidium copper phosphates

“…Oxysalts with mineral-like structures containing 'additional' oxygen atoms and OH groups that can be described in terms of anion-centered tetrahedra (Krivovichev & Filatov, 2001;Krivovichev, Mentré et al, 2013) as having anion-centered [(OH)Me 3 ] triangles and [OMe 4 ] tetrahedra (Me = Cu, Ni, Fe, Zn etc.) attract interest due to their magnetic properties controlled by the local structure of the oxygen-based copper polycations (Aksenov et al, 2017;Yamnova et al, 2017;Volkova & Marinin, 2017, 2018a.…”