Du Yan-Ling, Bu Hong-Xia, Ji Cheng-Jie, Zhang Xin-Miao, Li Cheng-Lin, Fang Xiao-Nan
College of Science and Technology, Shandong University of Traditional Chinese Medicine, Jinan 250355, China.
Phys Chem Chem Phys. 2019 Aug 21;21(33):18170-18178. doi: 10.1039/c9cp00746f.
Half-metallic materials have gained a lot of attention because of their unique properties and applications in spintronic devices. Despite the fact that these materials have been studied by several research groups there are very limited studies on their heterostructure (HS) systems. In the current study we have investigated the electronic and magnetic properties of (LaAlO3)6.5/(SrTiO3)2.5(111) HS using density functional theory (DFT) calculations. We demonstrate that the system exhibits a 100% spin-polarized two-dimensional electron gas (2DEG) which is extremely confined to the Ti 3d orbitals of the SrTiO3 layers. In particular, this system can keep its half-metallic properties under different in-plane strains from -3 to 2%. This property proves that this material has relatively stable half-metallic properties. In addition, the conducting and magnetic ground states of the system can also be tailored by changing in-plane strain and interfacial cation intermixing of La and Sr (Sr ⇔ La intermixing). By increasing the in-plane lattice parameters, this system has the ability to evolve from a nonmagnetic to a ferromagnetic metal and then to a half-metal and by further increasing the in-plane lattice parameter it becomes a ferromagnetic insulator. Sr ⇔ La intermixing can destroy the original half-metallic properties and the system exhibits an AFM Mott-type insulator phase. Our results demonstrate that the system has high potential for application in the field of spintronics, and opens the prospect of using LaAlO3/SrTiO3(111) HSs to explore quantum phase transitions.
半金属材料因其独特的性质以及在自旋电子器件中的应用而备受关注。尽管这些材料已被多个研究小组进行了研究，但对其异质结构（HS）系统的研究却非常有限。在本研究中，我们使用密度泛函理论（DFT）计算研究了(LaAlO3)6.5/(SrTiO3)2.5(111) HS的电子和磁性性质。我们证明该系统表现出100%自旋极化的二维电子气（2DEG），其极度局限于SrTiO3层的Ti 3d轨道。特别是，该系统在从-3%到2%的不同面内应变下能够保持其半金属性质。这一性质证明该材料具有相对稳定的半金属性质。此外，通过改变面内应变以及La和Sr的界面阳离子混合（Sr ⇔ La混合），还可以调整该系统的导电和磁性基态。通过增加面内晶格参数，该系统能够从非磁性金属演变为铁磁金属，再演变为半金属，进一步增加面内晶格参数时则变为铁磁绝缘体。Sr ⇔ La混合会破坏原有的半金属性质，系统呈现出反铁磁莫特型绝缘体相。我们的结果表明该系统在自旋电子学领域具有很高的应用潜力，并为利用LaAlO3/SrTiO3(111) HSs探索量子相变开辟了前景。
