Tuning the Invar effect in Fe-based bulk metallic glasses by pressure-induced polyamorphism

The Invar effect, observed in ferromagnetic bulk metallic glasses (BMGs), cannot be explained by existing theories because the BMGs lack the crystalline structure. High-pressure high-temperature Extended X-Ray Absorption Fine Structure (EXAFS) experiments will reveal whether the Invar effect in amorphous materials is also accompanied by a spin-volume correlation. It will shed light on the pressure-induced atomic rearrangement and why the Invar effect is universal in BMGs but rare in crystalline materials. Furthermore, it is possible via the Invar effect to determine the pressure-dependence of the Curie temperature and to quantify the magnetic contribution to thermal expansion.