Joya Cooley, Ph.D.
California State University, Fullerton
Dr. Joya Cooley has been an assistant professor at the California State University, Fullerton since the Fall of 2020. Previously, Dr. Cooley was a postdoctoral scholar in the UC Santa Barbara Materials Research Laboratory under the supervision of Prof. Ram Seshadri. Dr. Cooley’s research interests are in functional materials toward energy conservation and other applications. Before her professional appointments, she obtained her doctoral degree in chemistry from the University of California, Davis in 2018 under the direction of Prof. Susan M. Kauzlarich, and bachelor’s degrees in chemistry (B.S.) and music (B.A.) from Furman University in Greenville, SC.
Magnetic refrigeration is accomplished through the magnetocaloric effect (MCE), a reversible temperature change that occurs in a material upon application of a magnetic field. The effect originates from cycling a material between two different magnetic states with high and low entropies, which in turn results in the material changing temperature.
In recent decades, this technology has been proposed as an environmentally friendly alternative to traditional vapor-compression technology, obviating the need for harmful chlorofluorocarbon refrigerants, and potentially capable of greater efficiency. The most promising magnetocaloric materials show large entropy changes upon application of a moderate magnetic field, quantified as the figure of merit ÄSM, which is often found in a magnetic material that has a magnetostructural transition. In such compounds, the magnetic transition is strongly coupled to a first-order structure change at the transition temperature.
Recent experimental and DFT-based work in predicting magnetocaloric performance across a range of transition metal magnets has identified a class of materials that are not known to show first-order magnetostructural transitions, and yet show strong magnetocaloric effect and appear to have a strong link between magnetism and structure. We have investigated several Mn-based binary and ternary materials using DFT as well as temperature-dependent structural and magnetic studies. We find that despite the lack of first-order structural transitions at their magnetic ordering temperatures, several materials show promising magnetocaloric performance correlated with their degree of magnetostructural coupling through magnetoelastic transitions.
Materials Science & Engineering Dept.