Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
KAUST Supercomputing Laboratory (KSL), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
ACS Nano. 2017 May 23;11(5):5011-5019. doi: 10.1021/acsnano.7b01743. Epub 2017 May 10.
The coexistence of ferromagnetic metallic phase and antiferromagnetic insulating phase in nanoscaled inhomogeneous perovskite oxides accounts for the colossal magnetoresistance. Although the model of spin-polarized electron transport across antiphase boundaries has been commonly employed to account for large magnetoresistance (MR) in ferrites, the magnetic anomalies, the two magnetic phases and enhanced molecular moment, are still unresolved. We observed a sizable MR in epitaxial spinel films (NiCoO) that is much larger than that commonly observed in spinel ferrites. Detailed analysis reveals that this MR can be attributed to phase separation, in which the perfect ferrimagnetic metallic phase and ferrimagnetic insulating phase coexist. The magnetic insulating phase plays an important role in spin filtering in these phase separated spinel oxides, leading to a sizable MR effect. A spin filtering model based on Zeeman effect and direct tunneling is developed to account for MR of the phase separated films.
纳米级非均匀钙钛矿氧化物中同时存在铁磁金属相和反铁磁绝缘相，这是巨磁电阻的原因。尽管自旋极化电子穿过反相边界的输运模型通常被用来解释铁氧体中的大磁电阻（MR），但是磁性异常、两个磁性相和增强的分子磁矩仍然没有得到解决。我们在外延尖晶石薄膜（NiCoO）中观察到了相当大的磁电阻（MR），比通常在尖晶石铁氧体中观察到的要大得多。详细分析表明，这种 MR 可以归因于相分离，其中完美的亚铁磁金属相和亚铁磁绝缘相共存。在这些相分离的尖晶石氧化物中，绝缘相在自旋过滤中起着重要作用，导致相当大的 MR 效应。我们基于塞曼效应和直接隧道效应开发了一个自旋过滤模型，以解释相分离薄膜的磁电阻。
