EAGER/Collaborative Research: CRYO: Engineering Atomically Thin Magnetic Materials for Efficient Solid-State Cooling at Cryogenic Temperatures

固态制冷方案可能会避免在1K以下的低温制冷中使用日益昂贵和稀缺的HE3。目前用于量子计算机、传感器和其他新技术操作的几乎所有商业超低制冷方法都需要HE3。这一初步构想的探索性研究资助项目将促进对超薄磁性材料放热过程的基本了解，从而为制造用于下一代固态制冷的磁性量子材料提供指导，促进纳米尺度上的热传输和冷却的基本物理，并帮助开发新类别的冷却技术。当某些磁性材料在低温下被磁化时，磁场的去除导致材料中曾经的磁性有序磁区的随机化。在这些多个磁区的形成或排序期间，材料中的热能被磁区吸收以重新定向它们的磁化，从而导致温度下降(即冷却)。可以设计原子薄磁性材料来控制和增强这些过程，从而为新兴的冷却设备打开未知的机会。这一努力将支持基础研究，以了解对这些磁性量子材料的修改，以实现高效的固态冷却，特别是在低于1K的低温下。将要开发的技术可以缓解与全球氦短缺相关的现有挑战。高中生和传统上代表性不足的群体的学生将接受包括量子材料制造、材料建模和模拟、低温硬件工程和低温实验在内的综合培训。这项研究将帮助这些学生掌握必要的知识和专业知识，成为未来量子科学和工程的劳动力。磁热效应在固态制冷方面具有巨大的潜力。然而，传统材料的磁热效应并不强，但如果结构相变可以伴随着磁相变，那么磁热效应就可以得到增强。然而，诱导这些一级相变传统上依赖于通过稀有和昂贵的稀土元素化合物对材料的组成进行修改。这项研究建议克服在理解和控制二维磁性材料以增强磁热效应方面的知识差距。研究小组将应用第一性原理材料模拟来了解二维磁体中的磁-结构关系，使用实验合成和加工来设计二维磁体，并应用磁电和磁光表征来量化结果的磁性。这项研究将阐明新兴二维磁体的局部原子结构、晶体结构和磁性之间的基本关系，为清洁冷却技术的低维磁结构的设计和优化提供有用的指导。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。

Solid-state cooling schemes can potentially circumvent the use of increasingly expensive and scarce He3 in cryogenic refrigeration below 1K. He3 is required in almost all current commercial ultralow refrigeration approaches used in the operation of quantum computers, sensors and other new technologies. This EArly-concept Grant for Exploratory Research (EAGER) project will advance the fundamental understanding of the heat-release process in ultrathin magnetic materials and thus provide the guidance to manufacture magnetic quantum materials for next-generation solid-state refrigeration, promoting the fundamental physics of heat transport and cooling on the nanoscale and aid in the development of new classes of cooling technologies. When certain magnetic materials are magnetized at low temperatures, the removal of the magnetic field leads to the randomization of once magnetically ordered domains within material. During the formation or ordering of these of multiple magnetic domains, thermal energy in the material is absorbed by domains to reorient their magnetizations, thereby leading to temperature drop (i.e., cooling). Atomically thin magnetic materials can be engineered to control and enhance these processes and thus could open up unexplored opportunities for emerging cooling devices. This effort will support the fundamental research to understand the modifications to these magnetic quantum materials to enable efficient solid-state cooling, particularly at cryogenic temperatures such as below 1K. The technology to be developed can mitigate the existing challenges associated with the worldwide shortage of helium. High-school students and students of traditionally underrepresented groups will be exposed to the comprehensive training including quantum materials fabrication, materials modelling and simulation, cryogenic hardware engineering, and low-temperature experiments. This research will help to equip these students with necessary knowledge and expertise as the workforce for the future quantum science and engineering.The magnetocaloric effect holds a great potential for solid-state refrigeration. However, the magnetocaloric effect in traditional materials is not strong, but it can be enhanced if a structural phase change can be concomitant with the magnetic phase transition. However, inducing these first-order phase transitions have conventionally relied on the compositional modification of the material through scarce and expensive rare-earth-elements based compounds. This research proposes to overcome the knowledge gap in the understanding and control of two-dimensional magnetic materials for an enhanced magnetocaloric effect. The research team will apply first-principles materials simulations to understand the magnetism-structure relationship in two-dimensional magnets, employ experimental synthesis and processing to engineer two-dimensional magnets, and apply magnetoelectric and magneto-optical characterizations to quantify the resultant magnetic properties. The research will elucidate the fundamental relationship between local atomic structures, crystalline structures and magnetic properties of emerging two-dimensional magnets, which could provide useful guidance for the design and optimization of low-dimensional magnetic structures for clean cooling technologies.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.