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

University Of Connecticut, Storrs CT

Investigators

Abstract

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.