Magnetocaloric materials: The search for new systems

The prospect of efficient solid-state refrigeration at room temperature is driving research into magnetic cooling engine design and magnetic phase transition-based refrigerants. I construct what I believe is the first Ashby-style map of magnetic refrigerant properties, comparing popular materials with limits derived from an idealized first-order transition model. This comparison demonstrates the potential for new magnetocaloric material systems to be established through structural control and optimization at the atomic-, nano- and microscales.