School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China.
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, People's Republic of China.
J Chem Phys. 2019 Mar 7;150(9):094704. doi: 10.1063/1.5063953.
Since the origin of magnetism in ZnO-based diluted magnetic semiconductors (DMSs) is still controversial, in this work, we presented a detailed study on the magnetic, structural, and electronic properties of wurtzite ZnO-based DMS systems with point and complex intrinsic defects. Two outer electrons from neutral oxygen vacancy (V) occupy the a orbital, making the inducted magnetic moment to be zero, while a cluster including three Vs leads to a magnetic moment of ∼1 μ. The magnetic moment of the system with a Zn vacancy (V) is 1.65 μ. When two neutral Vs in different relative distances were created in respective supercells, the systems showed different magnetic moments induced by the unequal level between the highest electron occupied orbital of the defect state introduced by different V sites and the valence band maximum. The system of a neutral O occupying an octahedral site gives rise to a magnetic moment of 2 μ, while zinc interstitial and antisite defects do not cause spin polarization. The system with a complex defect of V and V is magnetic when those vacancies are adjacent but still do not cause the compensation effect. The oxygen interstitial defect is unstable, and V easily turns into the complex defect. We suggest that V clusters and V complex defects could likely be the origin of ferromagnetism in undoped ZnO.
由于 ZnO 基稀磁半导体（DMS）中磁的起源仍存在争议，在这项工作中，我们对具有点和复杂本征缺陷的纤锌矿 ZnO 基 DMS 系统的磁、结构和电子性质进行了详细研究。中性氧空位（V）的两个外层电子占据 a 轨道，使感应磁矩为零，而包含三个 V 的团簇则导致约 1 μ 的磁矩。具有 Zn 空位（V）的系统的磁矩为 1.65 μ。当在各自的超晶胞中创建两个具有不同相对距离的中性 Vs 时，系统表现出由不同 V 位引入的缺陷态最高电子占据轨道与价带最大值之间不同能级引起的不同感应磁矩。占据八面体位置的中性 O 引起的磁矩为 2 μ，而锌间隙和反位缺陷不会引起自旋极化。当相邻空位时，具有 V 和 V 复杂缺陷的系统具有磁性，但仍不会引起补偿效应。氧间隙缺陷不稳定，V 容易变成复杂缺陷。我们认为 V 团簇和 V 复合物缺陷可能是未掺杂 ZnO 中铁磁性的起源。
