Charge ordering in PrCuMn6O12 and its behavior under pressure.

Polycrystalline PrCuMn₆O₁₂ sample has been successfully synthesized. It has been characterized by x-ray diffraction (XRD), magnetic and magnetotransport measurements at ambient pressure, and transport property measurements under pressures. From the refinements of XRD data, a cubic phase and a trigonal phase with charge ordering state were identified at higher and lower temperatures, respectively. The temperature dependence of the resistance indicates that the phase transition is a first-order transition. Both effective paramagnetic moments of the trigonal and cubic phases can be explained by orbital moment freezing theory. The transport property of the trigonal phase has been fitted with Mott’s law for variable range hopping. Though the magnetoresistance value is not large, the pressure-induced resistance value change of PrCuMn₆O₁₂ is positive and achieves 264.8%. The cubic phase is suppressed under pressure and transformed to the trigonal phase at 15 kbar, indicating favor of the charge ordering state under pressure. [ABSTRACT FROM AUTHOR]