Zero-field cooling exchange bias induced by spin metastable state in MnNiGa system

The existence of the spin metastable state in magnetic materials often causes novel physics including magnetization jumps, metamagnetic transition, and skyrmions. In this paper, we design the occupancy of Mn atoms in the MnNiGa system, and based on first-principles calculations, we anticipate the existence of spin metastable state in Mn2Ni1.5Ga0.5. Therefore, Mn2Ni2− x Ga x ( x =0.36–0.60) is selected as the research platform to carry out related research. The experimental results show that near the composition of Mn2Ni1.5Ga0.5, the lattice constant, crystal axis ratio, DC and AC magnetic test all have abnormal changes, and the zero-field cooling exchange bias is observed, which indicates the dual effects of the spin metastable state on structure and magnetic structure, and proves the dominant effect of spin metastable state on zero-field cooling exchange bias. This work provides a new idea for the design of spin metastable states in magnetic materials, and a new method for the realization of a zero-field cold exchange bias system.