Carrier and vacancy mediated ferrimagnetism in Cu doped rutile TiO2
Carrier and vacancy mediated ferrimagnetism in Cu doped rutile TiO2
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DOI：
10.1039/d0tc05654e
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发表时间：
2021-03
影响因子：
6.4
通讯作者：
Qiaolu Lin;N. Xu;Gongping Li;Z. Qian;Huan Liu;Renheng Wang
中科院分区：
文献类型：
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作者：
Qiaolu Lin;N. Xu;Gongping Li;Z. Qian;Huan Liu;Renheng Wang
Cu掺杂TiO 2有助于理解TiO 2基稀磁半导体的磁性起源。因此，在此，我们计算了具有不同价态和浓度的Cu取代Zn以及Cu取代和空位复合缺陷的TiO 2系统。当置换比为1/48时，仅在Cu_0置换体系中出现铁磁性。当Cu掺杂浓度增加到1/24时，Cu ~（2+）掺杂体系在（111）方向沿着且未被空区（低电荷密度区）隔开时，也表现出铁磁基态。Cu替代和氧空位复合缺陷系统由于空位诱导的载流子而容易极化。载流子改变了缺陷周围Ti离子的成键状态，产生剩余磁矩，但载流子对电子结构的贡献存在饱和极限。在2 × 2 × 2超原胞中，氧空位导致两个Cu替代之间形成非铁磁耦合. Cu替代和Ti空位复合缺陷导致p-d杂化减弱，缺陷引起的晶格畸变和Cu-O键的强相互作用是铁磁性的来源。Cu掺杂单晶TiO 2样品的室温铁磁性可能由空位或载流子介导。
Cu doped TiO2 can help to understand the magnetic origin of TiO2-based diluted magnetic semiconductors. As such, herein, we calculated the systems of TiO2 with different valence states and concentrations of Cu substituted for Zn as well as Cu substitution and vacancy complex defects. For the substitution ratio of 1/48, ferromagnetism appears only in Cu0 substitution system. By increasing the concentration of Cu to 1/24, Cu2+ substitution system also shows a ferromagnetic ground state when the Cu substitutions are not separated by empty regions (low charge density regions) and along the (111) direction. The Cu substitution and oxygen vacancy complex defect systems are easily polarized due to carriers induced by vacancy. Carriers change the bond of Ti ions around the defect, and arouse residual magnetic moment; however, the contribution of carriers to the electronic structure had a saturation limit. Oxygen vacancy leads to the formation of non-ferromagnetic coupling between two Cu substitutions in a 2 × 2 × 2 supercell. Cu substitution and Ti vacancy composite defect give rise to the weakening of p–d hybridization, and the lattice distortion caused by defects and the strong interaction of Cu–O bond is the source of ferromagnetism. The room-temperature ferromagnetism in Cu doped monocrystalline TiO2 samples could be mediated by vacancies or carriers.