Frustrated antiferromagnetic spin chains of edge-sharing tetrahedra in volcanic minerals K3Cu3(Fe0.82Al0.18)O2(SO4)4 and K4Cu4O2(SO4)4MeCl

摘要

The calculation of the sign and strength of magnetic interactions in twononcentrosymmetric minerals (klyuchevskite, K3Cu3(Fe0.82Al0.18)O2(SO4)4 andpiipite, K4Cu4O2(SO4)4Cu0.5Cl) has been performed based on the structural data.As seen from the calculation results, both minerals comprisequasi-one-dimensional frustrated antiferromagnets. They contain frustrated spinchains from edge-sharing Cu4 tetrahedra with strong antiferromagnetic couplingswithin chains and very weak ones between chains. Strong frustration of magneticinteractions is combined with the presence of the electric polarization intetrahedra chains in piipite. The uniqueness of magnetic structures of theseminerals caused by peculiarities of their crystal structures has beendiscussed. Keywords: Frustrated quasi-one-dimensional antiferromagnets,tetrahedral spin chains, klyuchevskite K3Cu3(Fe0.82Al0.18)O2(SO4)4, piypiteK4Cu4O2(SO4)4MeCl