Li Weiwei, Zhao Run, Wang Le, Tang Rujun, Zhu Yuanyuan, Lee Joo Hwan, Cao Haixia, Cai Tianyi, Guo Haizhong, Wang Can, Ling Langsheng, Pi Li, Jin Kuijuan, Zhang Yuheng, Wang Haiyan, Wang Yongqiang, Ju Sheng, Yang Hao
Jiangsu Key Laboratory of Thin Films, School of Physical Science and Technology, Soochow University, Suzhou 215006, China.
Sci Rep. 2013;3:2618. doi: 10.1038/srep02618.
Oxygen vacancies (V(O)) effects on magnetic ordering in Eu₀.₅Ba₀.₅TiO₃₋δ (EBTO₃₋δ) thin films have been investigated using a combination of experimental measurements and first-principles density-functional calculations. Two kinds of EBTO₃₋δ thin films with different oxygen deficiency have been fabricated. A nuclear resonance backscattering spectrometry technique has been used to quantitatively measure contents of the V(O). Eu₀.₅Ba₀.₅TiO₃ ceramics have been known to exhibit ferroelectric (FE) and G-type antiferromagnetic (AFM) properties. While, a ferromagnetic (FM) behavior with a Curie temperature of 1.85 K has been found in the EBTO₃₋δ thin films. Spin-polarized Ti(3+) ions, which originated from the V(O), has been proven to mediate a FM coupling between the local Eu 4f spins and were believed to be responsible for the great change of the magnetic ordering. Considering the easy formation of V(O), our work opens up a new avenue for achieving co-existence of FM and FE orders in oxide materials.
利用实验测量和第一性原理密度泛函计算相结合的方法，研究了氧空位（V(O)）对Eu₀.₅Ba₀.₅TiO₃₋δ（EBTO₃₋δ）薄膜中磁有序的影响。制备了两种具有不同氧缺陷的EBTO₃₋δ薄膜。采用核共振背散射光谱技术定量测量V(O)的含量。已知Eu₀.₅Ba₀.₅TiO₃陶瓷具有铁电（FE）和G型反铁磁（AFM）特性。然而，在EBTO₃₋δ薄膜中发现了居里温度为1.85 K的铁磁（FM）行为。源自V(O)的自旋极化Ti(3+)离子已被证明介导了局部Eu 4f自旋之间的FM耦合，并被认为是磁有序发生巨大变化的原因。考虑到V(O)易于形成，我们的工作为在氧化物材料中实现FM和FE序的共存开辟了一条新途径。
