Defect-induced modulation of the exchange anisotropy by swift heavy ion irradiation in Ni81Fe19/Ir7Mn93 bilayers

IF 1.4 3区物理与天体物理 Q3 INSTRUMENTS & INSTRUMENTATION

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms Pub Date : 2024-07-18 DOI:10.1016/j.nimb.2024.165466

Sanjay Kumar Kedia , Ambuj Tripathi , Sujeet Chaudhary

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Abstract

This study investigates the influence of swift heavy ion irradiation on exchange anisotropy (H_EA) and coercivity (H_C) in a set of top-pinned SiO_x/Cu/Ni₈₁Fe₁₉/Ir₇Mn₉₃/Ta bilayers fabricated by ion beam sputtering at room temperature (RT) in presence of an in-plane in situ static field of 1 kOe. Subsequently, the bilayers were subjected to a magnetic annealing process at 300 °C for an hour in the presence of a 3.5 kOe magnetic field. By systematically increasing the Au ion fluences from pristine to 3.3 × 10¹¹ ion/cm², the positive exchange anisotropy (PEA) and negative exchange anisotropy (NEA) were found to be enhanced by 10 Oe and ∼178 Oe, respectively. However, once the ion fluences surpassed the necessary threshold of 3.3 × 10¹¹ ion/cm² required for defect creation/pinning centers in the antiferromagnetic (AF) layer, a reduction in both $H_{EA}$ and $H_{C}$ was observed due to the interfacial mixing. The enhancement in PEA and NEA is attributed to the creation of defects or hyperthermal heating in the AF layer as a consequence of ion irradiation. These experimental results align with the framework of the diluted antiferromagnetic model. The persistent training effect, which is observed even after irradiation, confirms the existence of a highly metastable interface between the NiFe/IrMn layer. Thus, ion irradiation emerges as a powerful tool for precisely tailoring the H_EA and H_C of the bilayers by systematically controlling the ion fluence.

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快速重离子辐照对 Ni81Fe19/Ir7Mn93 双层中交换各向异性的缺陷诱导调制

本研究探讨了快速重离子辐照对在 1 kOe 的面内原位静磁场作用下，室温（RT）下通过离子束溅射制备的一组顶销 SiOx/Cu/Ni81Fe19/Ir7Mn93/Ta 双电层中的交换各向异性（HEA）和矫顽力（HC）的影响。随后，在 3.5 kOe 磁场作用下，将双层膜在 300 °C 下进行一小时的磁退火处理。通过有计划地将金离子通量从原始水平提高到 3.3 × 1011 离子/cm2，发现正交换各向异性（PEA）和负交换各向异性（NEA）分别增强了 10 Oe 和 ∼ 178 Oe。然而，一旦离子通量超过反铁磁（AF）层中产生缺陷/钉化中心所需的 3.3 × 1011 离子/平方厘米的必要阈值，就会观察到由于界面混合而导致的 HEA 和 HC 的降低。PEA 和 NEA 的增强归因于离子辐照在 AF 层中产生的缺陷或超热加热。这些实验结果符合稀释反铁磁模型的框架。即使在辐照之后也能观察到持续的训练效应，这证实了镍铁/锰铁层之间存在一个高度陨落的界面。因此，离子辐照是通过系统控制离子通量来精确定制双层膜的 HEA 和 HC 的有力工具。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms 物理-核科学技术

CiteScore

2.80

自引率

7.70%

发文量

231

审稿时长

1.9 months

期刊介绍： Section B of Nuclear Instruments and Methods in Physics Research covers all aspects of the interaction of energetic beams with atoms, molecules and aggregate forms of matter. This includes ion beam analysis and ion beam modification of materials as well as basic data of importance for these studies. Topics of general interest include: atomic collisions in solids, particle channelling, all aspects of collision cascades, the modification of materials by energetic beams, ion implantation, irradiation - induced changes in materials, the physics and chemistry of beam interactions and the analysis of materials by all forms of energetic radiation. Modification by ion, laser and electron beams for the study of electronic materials, metals, ceramics, insulators, polymers and other important and new materials systems are included. Related studies, such as the application of ion beam analysis to biological, archaeological and geological samples as well as applications to solve problems in planetary science are also welcome. Energetic beams of interest include atomic and molecular ions, neutrons, positrons and muons, plasmas directed at surfaces, electron and photon beams, including laser treated surfaces and studies of solids by photon radiation from rotating anodes, synchrotrons, etc. In addition, the interaction between various forms of radiation and radiation-induced deposition processes are relevant.