Charge transfer instability in a mixed Ir/Rh honeycomb lattice in Li2Ir1−xRhxO3 solid solution

Abstract

The solid solution series Li2Ir1-xRhxO3 is synthesized for several values of x between 0 and 1. The compounds possess a monoclinic layered structure (space group C2/m) throughout the solid solution range with the lattice constants following Vegard's relationship. Magnetization and resistivity data below room temperature are presented. The effective magnetic moment (μeff) is reduced below the value obtained by interpolating between the end-members, presumably due to nearest neighbor charge exchange leading to non-magnetic Ir5+/Rh3+ pairs. Surprisingly, the degree of reduction of μeff cannot be explained by a random mixture of Ir and Rh and, in particular, is strongly asymmetric around x = 0.5. This anomalous moment reduction possibly results from the difference in on-site Coulomb repulsion between Ir and Rh ions.