Coexistence of Weak Ferromagnetism and Paramagnetism in T'-Pr_(2-x)Ce_xCuO_(4+α-δ) Nanoparticles

摘要

The coexistence of ferromagnetism and paramagnetism of T'-Pr_(2-x)Ce_xCuO_(4+α-δ) (T'-PCCO) nanoparticles with x = 0, and 0.10 have been studied intensively in the normal state. All samples were synthesized by a chemically dissolved method using HNO_3 as a dissolving agent. The calcination process was performed at 1000oC for 15 h in air and followed by reduction annealing at 700oC in argon atmosphere for 10 h. All samples were first characterized by an x-ray diffraction (XRD) measureemnts followed by Rietveld and Maximum Entropy Method (MEM) analyseis. The result confirms the Ce-dependence and reduction annealing effect on the electron density at around the Cu site. The magnetic characterization was performed by using vibration sample magnetometer (VSM) indicating weak ferromagnetic properties at x = 0 and dominant paramagnetic properties at x = 0.10 at room temperature. Moreover, the weak ferromagnetic feature seems to remain after the annealing process. This signifies the coexist of weak ferromagnetism and paramagnetism at the normal state due to a number of oxygen vacancies in the crystal structure.