Ferrimagnetism and possible double perovskite structure in half Cr-doped YMn_(0.5)Cr_(0.5)O_3

摘要

Half Cr-doped YMn_(0.5)Cr_(0.5)O_3 polycrystalline has been synthesized by means of a standard solid-state reaction method. Powder X-ray diffraction gives evidence that the sample is a single phase of orthorhom-bic (Pbnm) or monoclinic (P2_1/c) structure as observed for other doped manganites, rather than the hex agonal structure as YMnO_3. Upon cooling, the magnetic susceptibility increases sharply at T_c ～75 K, indicating a magnetic ordering occurs. The detailed analysis on the paramagnetic behavior at higher tem peratures reveals that the low-temperature order is a ferrimagnetic state. The electrical transport prop erties show an insulator behavior dominated by the adiabatic small polaron hopping mechanism with high thermal activation energy. The results indicate that the ferromagnetic double exchange (DE) inter action is unreasonable in Cr-doped manganites.