Magnetic Phase Diagrams of YVO^sub 3^ and TbVO^sub 3^ under High Pressure

Magnetic states in R VO ... ( R = Y, Tb) were investigated using low-temperature and high-pressure neutron-diffraction techniques, and the pressure-temperature magnetic phase diagrams were clarified up to 6.2 GPa. We elucidated that, on application of pressure, the magnetic ground state changes from C -type spin ordering ( C -SO) to G -type spin ordering ( G -SO); this corresponds to the orbital ground-state switching from G -type orbital ordering ( G -OO) to C -type orbital ordering ( C -OO). It is also interesting that the G -SO transition occurs simultaneously with the C -OO transition, but not with the G -OO one. When the transition temperature of C -OO exceeds that of G -OO under high pressure, the G -OO phase vanishes completely, and a simultaneous spin and orbital order-disorder phase transition occurs. Such a transition is the first case in perovskite-type transition-metal oxides. (ProQuest: ... denotes formulae/symbols omitted.)