Perpendicular magnetic anisotropy in garnet-type ferromagnetic insulators used for inducing T-symmetry break in topological insulators

我想通过实验探索石榴石薄膜的物理性质和局限性。磁性矫顽力、各向异性和剩余磁化等特性将被量化和讨论。我计划总结这些特性与薄膜生长条件、化学计量、薄膜厚度和晶体结构的关系。此外，我想通过实验证明拓扑绝缘体中具有面外取向的邻近感应磁性。本项目的主要目标是通过脉冲激光沉积（PLD）可重复地创建和控制铁磁石榴石薄膜Tm3Fe5O12 (TmIG)，具有可控制的垂直磁各向异性（PMA），其矫顽力和磁化强度。所测磁性能的系统趋势将与化学计量学和晶体学性质相关联。第二个目标将包括对不同类型的稀土石榴石进行更广泛的研究。潜在的替代材料有：具有高磁致伸缩（和磁光活性）的铈，已经用于液相外延石榴石薄膜以促进PMA的镝，以及用Al或Ga稀释Fe以降低磁化强度，从而降低平面内各向异性，这将通过各自化学测量的自制PLD靶来实现。最后，通过拓扑绝缘体（TI）的后续生长，将实验研究是否存在可能的感应磁性（提升简并）进入表面TI态。

I want to experimentally explore the physical properties and limitations of garnet thin films. Characteristics like magnetic coercivity, anisotropy and remanent magnetization will be quantified and discussed. I plan to conclude how these properties relate to the thin film growth conditions, stoichiometry, film thickness and crystal structure. Furthermore, I want to experimentally demonstrate proximity-induced magnetism with out-of-plane orientation in topological insulators.The primary objective of this project is to reproducibly create and controll the ferromagnetic garnet thin film Tm3Fe5O12 (TmIG) via pulsed laser deposition (PLD) with controllable perpendicular magnetic anisotropy (PMA) in respect to its coercivity and magnetization. Systematic trends of measured magnetic properties will be correlated to the stoichiometric and crystallographic properties. The secondary objective would include a broader study of different types of rare-earth garnets. Potential substituent materials are cerium, with its high magnetostriction (and magnetooptical activity), dysprosium, already used in liquid phase epitaxy garnet films to promote PMA, and dilution of the Fe with Al or Ga to reduce the magnetization and therefore the in-plane anisotropy which will be realized using self made PLD targets of the respective stoichiometry. Finally, by subsequent growth of topological insulators (TI), the existence of possible induced magnetism (lifting of the degeneracy) into the surface TI states will be experimentally investigated.