[论文解读] Direct Laser Writing of Ferromagnetic Nickel Utilizing the Principle of Sensitized Triplet-Triplet Annihilation Upconversion

K. Kühl, Katharina Rediger+6 more|arXiv (Cornell University)|Mar 10, 2026

Magnetic properties of thin films被引用 0

一句话总结

本文提出一种在环境条件下通过将原位脱氧、sTTA-UC 增敏和光还原结合起来，直接激光写入以制备镍磁性微结构的新方法。

ABSTRACT

Direct laser writing of ferromagnetic microstructures is of great interest for sensing and data storage in compact three-dimensional architectures. However, reliable direct laser writing of metallic and even more so ferromagnetic materials remains a major challenge. Here, we present a novel photoresist suitable to direct laser write ferromagnetic nickel based on sensitized triplet-triplet annihilation upconversion. By combining an in-situ photochemical deoxygenation process with a sensitized triplet-triplet annihilation upconversion process as well as a photoreduction of Ni2+ ions, the deposition of metallic nickel is enabled under ambient conditions. Using this approach, nickel structures are fabricated as a proof of concept. Scanning electron microscopy and EDX analysis confirm the spatially confined deposition of nickel, while magnetic characterization by vibrating sample magnetometry and scanning NV magnetometry demonstrate the ferromagnetic nature of the printed structures. This work presents a major step forward in extending the possibilities of direct laser writing to metallic and ferromagnetic materials.

研究动机与目标

• Develop a direct laser writing approach to fabricate metallic nickel structures under ambient conditions.
• Integrate deoxygenation, sTTA-UC, and photoredox chemistry to drive nickel deposition from Ni2+ in a photoresist.
• Demonstrate the ferromagnetic nature and material density of printed nickel structures.

提出的方法

• Use a photoresist containing perylene (annihilator), Erythrosine B (sensitizer), NiCl2·6H2O (nickel source), and DIPEA (electron donor) in DMI.
• Employ a 532 nm continuous-wave laser to initiate sTTA-UC and photoreduction within a locally deoxygenated volume.
• Implement in situ deoxygenation by a photosensitizer cycle that generates singlet oxygen which is scavenged by the solvent (DMI).
• Promote nickel deposition via two‑photon‑like nonlinear processes through sTTA-UC to achieve photoreduction of Ni2+ to Ni0.
• Characterize printed structures by SEM/EDX, VSM, and scanning NV magnetometry to verify morphology, composition, and ferromagnetism.

实验结果

研究问题

• RQ1 Can a sTTA-UC based photochemical route enable direct laser writing of metallic nickel under ambient conditions?
• RQ2 What are the roles of deoxygenation, photosensitizer, annihilator, and electron donor in enabling Ni deposition?
• RQ3 Do printed nickel structures exhibit ferromagnetic behavior and what are their magnetic characteristics?

主要发现

• Nickel structures were successfully printed with high material density (~96% density).
• VSM measurements show a saturation magnetization of 486 ± 91 kA/m and a remanence of ~11% of Ms.
• The printing speed can reach up to 100 μm/s under cw 532 nm excitation.
• NV magnetometry confirms ferromagnetic ordering and reveals measurable stray fields consistent with remanence.
• The results suggest domain-wall pinning and possible lamellar or fragmented domain states due to microstructure features.