Large exchange bias effect in the super spin glass state of Mn50Ni38Al12 alloy

A large exchange bias field (HEB) of 5.3 kOe which so far, is the largest value found in MnNi-based alloys, was observed in Mn50Ni38Al12 ribbon. DC and AC magnetic measurements show super spin glass (SSG) behavior below 130 K and superparamagnetic behavior above this temperature. Different from other systems, the pinning and pinned phases are both SSG. Due to the high content of Mn and low content of Al there exists considerable disorder in Mn50Ni38Al12 which is responsible for the large HEB.