Softening of Hard Magnetic Behavior and the Maximum Coercive Field in Zr2RhTl as Revealed by Effective Field Theory

The present study investigated the magnetic hysteresis properties (coercivity and remanent magnetization) of the Zr2RhTl Heusler alloy using effective field theory (EFT). The study found that the coercive field of Zr2RhTl reaches a maximum at a specific critical temperature, Tch, at which the hardness of magnetic materials increases with the coercive field. This behavior is called the “critical hardness temperature (Tch)”. The hardness of the Zr2RhTl Heusler alloy increases with temperature until Tch, reaching a maximum at Tch. In contrast, it exhibits soft magnetic behavior at T < Tch and T > Tch. We suggest that this maximum hardness behavior can enable a new class of thermo-hardness sensors (THSs) and actuators (THAs).