Tailoring ferrimagnetic properties using proximity effects in Co/Tb-Co bilayers

The magnetic properties of Co/Tb-Co bilayers are studied across a broad range of parameters (the thicknesses of the two layers and the composition of the alloy layer) using both experimental techniques and atomistic simulations. This work demonstrates the ability to precisely modify the compensation point of Tb-Co alloy thin films by adding a Co underlayer with a specified thickness. Furthermore, the range of parameters are identified for which the magnetization reversal of the alloy and Co layers occurs synchronously and provide a simple expression for calculating the effective composition of the bilayer system. Additionally, it is shown that an exchange-spring magnet behavior can emerge when the alloy is Tb-dominant and the Co underlayer thickness exceeds a critical threshold. It is also demonstrated that for Tb concentrations where the alloy layer is expected to be paramagnetic, the exchange coupling with the Co layer locally induces ferrimagnetic order near the interface, leading to a second transition back to Co dominance. This dataset includes: Magneto-optic measurements using P-MOKE magnetometer The results of atomistic simulation using the VAMPIRE package This work was supported by National Science Centre Poland under OPUS funding Grant No. 2020/39/B/ST5/01915 at the Institute of Molecular Physics of the Polish Academy of Sciences.本研究结合实验技术与原子级模拟手段，在宽参数范围（涵盖双层膜各自厚度与合金层组分）内系统探究了Co/Tb-Co双层膜的磁学特性。本工作证明，通过沉积特定厚度的Co底层，能够精准调控Tb-Co合金薄膜的补偿点。此外，本研究明确了合金层与Co层磁化反转同步发生的参数区间，并推导出用于计算该双层体系有效组分的简洁表达式。 研究还发现，当合金层以Tb为主要组分且Co底层厚度超出临界阈值时，体系可呈现交换弹簧磁体（exchange-spring magnet）行为。进一步结果表明，当合金层的Tb浓度处于顺磁性区间时，与Co层之间的交换耦合会在界面处局部诱导亚铁磁有序，进而引发第二次相变，使体系重新表现出Co主导的磁特性。 本数据集包含： - 采用纵向磁光克尔效应（Polar Magneto-Optic Kerr Effect, P-MOKE）磁强计完成的磁光测量结果 - 基于VAMPIRE软件包运行的原子级模拟结果 本研究获得波兰国家科学中心OPUS项目（项目编号：2020/39/B/ST5/01915）以及波兰科学院分子物理研究所的资助。