EAGER: CRYO: New Quantum Elastocaloric Demagnetization Refrigeration for the Millikelvin Range

该项目由化学、生物工程、环境和运输系统部和材料研究部联合支持。开发可冷却到1开尔文以下的替代制冷技术的需求日益增长，以支持新兴应用，如量子传感器和量子计算机。目前，液氦冰箱主要用于达到1开尔文以下的温度。由于氦的日益稀缺，以及现有技术的便携性和可扩展性的缺乏，替代冷却方法引起了人们的极大兴趣。固态制冷技术在部分取代氦技术方面已经取得了一定的成功，例如通过磁场的降低和增加循环冷却磁性固体材料的技术。然而，它也有明显的缺点，包括对几个特斯拉的磁场要求很高。本项目提出了一种基于机械应变固态磁性材料的低场冷却技术。这种方法预计是可持续的、可移植的，并在电子芯片级别部署，提供了一条实现可伸缩性的途径。在这个项目中，一群不同的学生将接受热学、材料和量子科学方面的培训。这项培训将通过在高级本科教学实验室开发侧重于低温冷却的新课程来提供，通过针对代表性不足的本科生的麦克奈尔方案在研究项目中提供，通过研究生水平的研究项目来提供。暑期将为当地高中教师提供开发现代热学教育演示的机会，作为量子研究的支持领域。这里提出的高风险高回报工作的总体目标是实现一种新的固态毫米波量子弹性热能绝热制冷技术，该技术将通过周期性施加弹性应变/应力来实现冷却循环，无论是在没有或有小磁场的情况下。在这个项目中，弹性应力/应变调谐将被用来在一种称为受阻磁体的特殊类型的磁性材料中诱导近零温度的相变。因此，这种新方法有望以高效率提供远低于1开尔文的冷却。为了评估受阻磁体的薄膜、单晶和块体陶瓷，将使用一系列独特的适用于应变下材料的表征工具：超导量子干涉器件显微镜、热成像、交流热容、磁化等。与其他一些固态冷却技术相比，所提出的应变驱动冷却技术有望提供更好的冷却功率和更低的温度。量子弹性热能绝热制冷方法有可能实现一项突破性的发现，取代其他平台，特别是在低磁场和芯片可扩展应用中，并可能对节能电子、量子计算和传感产生变革影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project is jointly supported by the Division of Chemical, Bioengineering, Environmental and Transport Systems and the Division of Materials Research.There is a growing demand to develop alternative refrigeration technology that can cool below 1 Kelvin for supporting emerging applications, such as quantum sensors and quantum computers. Currently, liquid helium refrigerators are mostly used to reach temperatures below 1 Kelvin. Due to the increasing scarcity of helium and lack of portability or scalability of the current technologies, alternative cooling methods are of great interest. Solid-state refrigeration technology, such as the one in which magnetic solid materials are cooled via cycles of decreasing and increasing magnetic field has been somewhat successful in partly replacing helium technology. However, it has significant drawbacks, including high magnetic field requirement of several Tesla. This project puts forward a low-field cooling technology based on mechanically strained solid-state magnetic materials. This approach is projected to be sustainable, portable, and deployed at the electronic chip level, providing a route to scalability. During this project, a diverse group of students will be trained in thermal, material and quantum sciences. This training will be provided through the development of a new curriculum focusing on low temperature cooling in advanced undergraduate teaching laboratory, in research projects through the McNair program for underrepresented undergraduate students and through graduate-level research projects. Summer research opportunities will be provided for local high school teachers to develop educational demos in modern thermal science as a quantum-supporting area of research.The overarching goal of the high-risk high-reward work propose here, which is jointly supported by the Division of Chemical, Bioengineering, Environmental and Transport Systems and the Division of Materials Research, is to realize a new solid-state millikelvin Quantum Elastocaloric Adiabatic Refrigeration technology in which a cooling cycle will be achieved via periodic application of elastic strain/stress, without or with small magnetic field. In this project, elastic stress/strain tuning will be used to induce near-zero temperature phase transitions in a special type of magnetic materials called frustrated magnets. Thus, this new method is expected to provide cooling well below 1 Kelvin with high efficiency. To evaluate thin films, single crystals and bulk ceramics of frustrated magnets, an array of uniquely adapted characterization tools for materials under strain will be employed: superconducting quantum interference device microscopy, thermal imaging, ac heat capacity, magnetization etc. The proposed strain-driven cooling technology is expected to provide superior cooling power and lower temperature in comparison to some other solid-state cooling technologies. The Quantum Elastocaloric Adiabatic Refrigeration approach has the potential to materialize into a groundbreaking discovery replacing other platforms, in particular in low magnetic field and on-chip scalable applications and may have transformational impact on energy-efficient electronics, quantum computing and sensing.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.