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

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.