EAGER: CRYO: Continuous Adiabatic Demagnetization Refrigeration Below 1K without Helium-3

EAGER（Early-concept Grant for Exploratory Research）支持建立与开发基于量子的系统（如计算机）所需的低温制冷相关的新技术的研究，从而促进科学进步，促进国家繁荣和安全。量子信息技术等领域的重要科学进步依赖于在低于1开尔文温度下的操作。基于磁性的冷却可以是本技术的替代方法。目前的磁冷却方法不支持连续操作，这是商业化的主要障碍。本项目研究将磁体构造成流体状，通过使磁制冷剂在闭环循环中循环来实现连续冷却的连续制冷方法。关键概念结合了低温物理学和纳米材料科学，可能为物理学，化学，材料科学和医学科学的各种尖端探索开辟新的跨学科能力和合作场所，并弥合与工业的差距。因此，保持美国的领导地位具有重要的战略意义。开发的新材料清洁环保，符合绿色标准，提高社会经济生活质量。该项目将培训参与者，特别是不同背景的学生，以实现研究和教育目标，并为未来的创新做好准备。绝热退磁制冷是一种可行的方法，可以在不使用氦-3的情况下达到低于1开尔文的温度。然而，目前使用固体顺磁材料的方法不仅将操作限制为单次冷却，而且还将基础温度限制为磁交换相互作用的水平。本项目旨在通过采用非相互作用的顺磁流体制冷剂来实现能够达到更低温度的连续绝热退磁冷却。该研究工作旨在通过研究各种表面积与体积比的中空顺磁性纳米颗粒与氦-4超流体的混合物来实现流体顺磁体，并实现漂浮条件。将进行实验，通过检测作为循环速率的函数的局部磁通量来表征循环中各种纳米颗粒密度的磁化和退磁效应。其目标是将磁化/退磁效率与冷却功率实时关联，从而优化冷却效果并实现精确的温度控制。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Early-concept Grant for Exploratory Research (EAGER) supports research establishing new technologies related to low-temperature refrigeration needed for the development of quantum-based systems, such as computers, thus promoting both the progress of science and advancing national prosperity and security. Important scientific advancements in areas such as quantum information technology rely on operation at temperatures below one Kelvin temperatures. Magnetically based cooling could be an alternative approach to the present technology. Present approaches to magnetic cooling do not support a continuous operation which is a major hindrance toward commercialization. This project researches a continuous refrigeration method by constructing a magnet in the form of a fluid and achieving continuous cooling by circulating the magnetic refrigerant within closed-loop cycles. The key concept combines low-temperature physics and nanomaterial science, potentially opening new interdisciplinary capabilities and collaboration venues for diverse cutting-edge exploration in physics, chemistry, material science, and medical science and bridging the gap to industry. Therefore, it is strategically important for maintaining U.S. leadership. The new materials to be developed are clean and environment-friendly, meeting the green standard to improve the social and economic qualities of lives. This project will train participants, especially students of diverse backgrounds, to achieve research and educational goals, and to be prepared for future innovations.Adiabatic demagnetization refrigeration is a viable approach to reaching temperatures below one Kelvin without using helium-3. However, the current method with solid paramagnetic materials not only restricts the operation to a single shot cooling but also limits the base temperature to the level of the magnetic exchange interaction. This project aims to achieve continuous adiabatic demagnetization cooling capable of reaching lower temperatures by adopting a noninteracting paramagnetic fluid refrigerant. The research work seeks to realize a fluid paramagnet through studying mixtures of hollow paramagnetic nanoparticles of various surface-to-volume ratios with a helium-4 superfluid and achieve a floating condition. Experiments will be carried out to characterize the magnetization and demagnetization effects for various nanoparticle densities in circulation by detecting the local magnetic flux as a function of the circulation rates. The goal is to correlate the magnetization/demagnetization efficiency in real-time with the cooling power, thus optimizing the cooling effect and achieving precise temperature control.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.