Integer spin-chain antiferromagnetism of the 4d oxide CaRuO3 with post-perovskite structure

A quasi-one-dimensional magnetism was discovered in the post-perovskite CaRuO3 (Ru4+: 4d(4), Cmcm), which is isocompositional with the perovskite CaRuO3 (Pbnm). An antiferromagnetic (AFM) spin-chain function with -J/k(B) = 350 K reproduces the experimental curve of the magnetic susceptibility vs temperature well, suggesting long-range AFM correlations. The anisotropic magnetism is probably owed to the d(yz)-2p(pi)-d(zx) and d(zx)-2p(pi)-d(yz) superexchange bonds along the a axis. The Sommerfeld coefficient of the specific heat is fairly small, 0.16(2) mJ mol(-1) K-2, indicating that the magnetism reflects the localized nature of the 4d electrons. This is an observation of an integer (S = 1) spin-chain AFM in the 4d electron system.