The Role of B-Site Distribution in Ca₂FeReO₆

Abstract

This study systematically investigates the spin glass behavior of the double perovskite Ca 2 FeReO 6 . Building on previous research, we developed a formula to quantify the distribution of ions at the B-site, incorporating next-nearest-neighbor interactions. Using molecular field theory and Monte Carlo simulations, we examined the influence of different arrangements of B-site ions on frustration effects. The B-site is divided into a-site and b-site, with the number of nearest neighbors from Fe a to Fe b (and vice versa) defined as Z x (Z y ). The strongest frustration occurs when Z x (or Z y ) ≈ 2 and Z y (or Z x ) ≈ 5, resulting in a radial pattern under comparable conditions. Significant frustration effects are also observed when Z x (or Z y ) ≈ 3 and Z y (or Z x ) ≈ 4. These effects are reflected in the variations in ground-state magnetization and the thermal energy step in relation to Z x and Z y . The model proposed in this study is applicable to most B-site disordered perovskite systems as well as other chemically disordered frustrated systems.