混合场中 (Pr1－yNdy)2/3Sr1/3MnO3体系磁转变行为研究

对(Pr1-yNdy)2/3Sr1/3MnO3(y=2/8,4/8,6/8)体系在42K—300K温度范围内混合场（即交流驱动场Hac与附加直流磁场H dc的叠加）下的磁转变行为进行了系统的实验研究. 结果表明，随着外加直流磁场强 度的增大，样品的直流磁化强度增大，交流磁化率逐渐减小；在混合场作用下，磁转变温度 （居里温度）附近样品交流磁化率的实部出现一个特征的尖峰. 对于(Pr1-yNdy)2/3Sr1/3MnO3体系，随着Nd掺杂量的增加，交流磁化率实部 的相对变化 (Eχ′=Δχ′/χ′dc)的峰值对应的温度降低，这一点与该系 统的磁电阻的变化规律一致. 对锰氧化物体系在混合场中的磁转变现象进行了讨论.关键词：锰氧化物混合场磁特性

Study on magnetic transition behavior for (Pr1-yNdy)2/3Sr1/3MnO3 system under superposed fields

The magnetic transition behaviors of (Pr1-yNdy)2/3Sr 1/3MnO3(y=2/8,4/8,6/8) polycrystalline samples under superposed ma gnetic fields (i.e., the superposed ac and dc magnetic field) were systematicall y studied at temperatures ranging from 42 to 300K. The results showed that the magnetization increases with the increase of magnetic field, and the real part of the ac susceptibility decreases as the superposed dc magnetic field increases . Under the superposed magnetic field, a characteristic sharp peak of the real p art of the susceptibility appears near the magnetic transition temperature (Curi e temperature). For the (Pr1-yNdy)2/3Sr1/3MnO 3 system, as the Nd content increases, the peak temperature of the relative variation of the real part of susceptibility (Eχ′=Δχ′/χ′ dc) decreases, in consistent with that of the magnetoresistivity of this sys tem. The magnetic transition behaviors under superposed magnetic fields for the manganite systems are discussed.