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。为了支持量子传感器和量子计算机等新兴应用，开发可以冷却到1开尔文以下的替代制冷技术的需求日益增长。目前，液氦冰箱主要用于达到低于1开尔文的温度。由于氦气的日益稀缺以及当前技术缺乏可移植性或可扩展性，替代冷却方法引起了极大的兴趣。固态制冷技术，如磁性固体材料通过减少和增加磁场的循环冷却，已经在一定程度上成功地取代了氦技术。然而，它也有明显的缺点，包括需要几个特斯拉的高磁场。本课题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，并部署在电子芯片级，提供了可扩展性的途径。在这个项目中，一群不同的学生将接受热、材料和量子科学方面的培训。这种培训将通过开发新的课程来提供，重点是在高级本科教学实验室中进行低温冷却，通过McNair计划为代表性不足的本科生提供研究项目，并通过研究生水平的研究项目。将为当地高中教师提供暑期研究机会，以开发现代热科学作为量子支持研究领域的教育演示。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的高风险高回报工作的总体目标是实现一种新的固态毫开尔文量子弹热绝热制冷技术，该技术通过定期施加弹性应变/应力来实现冷却循环，没有或具有小磁场。在这个项目中，弹性应力/应变调谐将用于诱导一种称为受挫磁铁的特殊磁性材料的近零温度相变。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。为了评估失效磁体的薄膜、单晶和大块陶瓷，将采用一系列独特的应变下材料表征工具：超导量子干涉装置显微镜、热成像、交流热容量、磁化等。与其他固态冷却技术相比，所提出的应变驱动冷却技术有望提供更好的冷却能力和更低的温度。量子弹性热绝热制冷方法有可能成为取代其他平台的突破性发现，特别是在低磁场和片上可扩展应用中，并可能对节能电子、量子计算和传感产生变革性影响。该奖项反映了美国国家科学基金会的法定使命，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 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.