Design of Mn–Mn distance for tunable spontaneous exchange bias in Heusler alloys

Abstract To accelerate the discovery of spontaneous exchange bias (SEB) materials and optimize its performance, reasonable design scheme is needed. Taking advantage of the extremely sensitive dependence of SEB on the value of molecular magnetic moments in the Mn-rich Heusler alloys, a design scheme of the Mn–Mn distance for SEB is proposed to tune the molecular magnetic moment in the Ni-rich Heusler alloys. Here, it is found that the Mn–Mn distance can be controlled in the Ni2Mn1.4In0.6-xAlx system. The experimental results show that SEB is achieved in Ni2Mn1.4In0.6-xAlx (x = 0.24–0.56), and the SEB field is indeed dominated by the Mn–Mn distance. Therefore, the Mn–Mn distance can tune the molecular magnetic moment, and then tune SEB. Our findings demonstrate that the design of the Mn–Mn distance is an effective method to tune SEB. This opens up a new approach to the development of SEB materials.