The ferromagnetic to antiferromagnetic crossover in chromium-based pyroxenes tuned via the Ge to Si ratio

Abstract

For the isotropic spin Cr3+-based (S = 3/2) chain-structure pyroxenes, NaCrGe2O6 is a ferromagnet while NaCrSi2O6 is an antiferromagnet, offering a platform for studying one-dimensional (1D) magnetic interactions. Here we describe our characterization of the NaCrGe2-xSixO6 (0 ≤ x ≤ 2) solid solution series, locating the ferromagnetic-to-antiferromagnetic crossover composition at x = 1.40. NaCrGe0.6Si1.4O6 has a close-to-zero Weiss temperature, which we attribute to a balance between the ferromagnetic and antiferromagnetic interactions in this pseudo-1D isotropic spin system.