Different exchange bias behavior caused by tuning glassy state in Ni₅₀Mn₃₇Ga₁₃ ribbons

Exchange bias plays a significant role in the application of spin valves and magnetic sensors. A spontaneous exchange bias field of 0.75 kOe can be observed in the annealed Ni₅₀Mn₃₇Ga₁₃ ribbons, while a giant exchange bias field of 6.14 kOe occurs in the quenched samples under field cooling. This is due to the different lattice parameters and microscopic morphology making the annealed and quenched samples, respectively, form superspin glass and spin glass embedded in the antiferromagnetic matrix. The conditions for superspin glass and spin glass to overcome the energy barrier of spin reconfiguration are different, resulting in the difference in exchange bias behavior. This work combines the magnetic properties with the crystal structure and microscopic morphology, providing a method of controlling the glassy state by heat treatments to regulate the exchange bias of Heusler alloys.