As basic science teaches us, changes in temperature can result in phase transitions in materials – like when water solidifies as ice in the freezing cold.
However, in some cases the temperature that triggers the change is different depending on whether the material is cooling down or warming up. This is known as aIt's not a transition you're likely to see in everyday life, requiring a layered compound crystalline solid called EuTe, huge temperature ranges, and a kilometer-long track for firing fast-moving charged particles deployed to create brilliant laser light.
While it's early days for this discovery, the team does have a few ideas about what might be happening: the particular way electrons are arranged in EuTecauses a secondary electronic crystal to form, and it could be that as this second layer moves and shifts, it creates different configurations in the hysteresis loop.