Unveiling the Mystery: Why Some Alloys Remain Unchanged When Heated

Researchers from the California Institute of Technology have discovered the secret behind the unusual behavior of Invar alloys, which do not change in size and density over a wide range of temperatures. By measuring the vibrational spectra and magnetism of Invar samples, the researchers found a delicate balance between thermal expansion caused by atom vibrations and magnetism. The interaction between vibrations and magnetism, such as altered frequencies of atom vibrations, helps maintain this balance. This finding could aid in understanding thermal expansion in other magnetic materials and developing materials for magnetic refrigeration.