Crossover behavior of the crystal structure and the relation to magnetism in perovskite RTiO₃

We found that a crossover behavior of the crystal structure at high temperatures dominates the magnetic state at low temperatures in the series of R TiO₃ (R is rare earth). At the crossover temperature, which exist only in the samples that become antiferromagnetic at lower temperatures, the temperature derivative of lattice constants changes its sign, and the crossover temperature approaches zero as the Neel temperature approaches zero in the phase diagram of the ionic radius of R vs temperature. This result indicates that the orbital state of the Ti ion dominates the low-temperature magnetic state in R TiO₃.