The interplay between A-site randomness and magnetic phase transition in half-doped manganite Pr0.5Ba0.5MnO3 (PBMO) was extensively investigated. The H/M versus M2 isotherms show that the A-site ordered PBMO undergoes a second-order magnetic phase transition from paramagnetism to ferromagnetism, whereas the A-site disordered PBMO exhibits a fluctuation-driven first-order transition arising from a competing order phase possibly existing in the paramagnetic state. A step-like transition in magnetization and resistivity with a sharp width of ΔH/H ~ 10−3 was only observed in the A-site partially ordered PBMO at 2 K, indicating that the metamagnetic transition is associated with a competition between randomly distributed short-range ferromagnetic and antiferromagnetic phases. These findings provide evidence that the A-site randomness not only suppresses A-type antiferromagnetism also moderately weakens long-range ferromagnetism in the A-site ordered PBMO.
Journal of Physics: Conference Series(JPCS) 400, 032047