New Nanomaterial Turns Magnetic When Heated

While fridge magnets are great for saving favorite recipes, modern magnetic materials are useful for improving fiber optics or quantum information sciences technology. If you zoomed in on most fridge magnets, you'd see the atoms arranged in a repeated lattice structure called a "spinel." These structures are made up of three types of atoms, generically referred to as atoms "A," "B" and "X." In a paper published Aug. 14 in the Journal of the American Chemical Society, UW researchers describe two new spinels made of silver, chromium and selenium ions. These are among the first spinels to include a silver ion in the "A" slot, the slot that determines the "vibe" of the spinel, or how it will react to various stimuli, such as light, heat or air. When exposed to air, the original spinel loses silver ions and transforms into the second spinel. The second spinel maintains its magnetic properties up to 400 Kelvin, or 260 degrees Fahrenheit; the original loses its magnetism at 152 K, or -185 F. This is the largest change ever documented in what is known as the Curie temperature, or the highest temperature at which a material is still magnetic. The researchers plan to continue to explore these two materials and what they can teach us about the fundamentals of magnetism.