Charge order melting and magnetic transition in Nd0.5(1+x)Ca0.5(1−x)Mn(1−x)CrxO3 system

The magnetic property of double doped manganite Nd0.5(1+x)Ca0.5(1−x)Mn(1−x)CrxO3 with a fixed ratio of Mn3+:Mn4+=1:1 has been investigated. For the undoped sample, it undergoes one transition from charge disordering to charge ordering (CO) associated with paramagnetic (PM)-antiferromagnetic (AFM) phase transition at T<250 K. The long range AFM ordering seems to form at 35 K, rather than previously reported 150 K. At low temperature, an asymmetrical M-H hysteresis loop occurs due to weak AFM coupling. For the doped samples, the substitution of Cr3+ for Mn3+ ions causes the increase of magnetization and the rise of Tc. As the Cr3+ concentration increases, the CO domain gradually becomes smaller and the CO melting process emerges. At low temperature, the FM superexchange interaction between Mn3+ and Cr3+ ions causes a magnetic upturn, namely, the second FM phase transition.