  The effect of ball milling on the structural, magnetic and exchange bias
properties of Ni50Mn36Fe2Sb12 Heusler alloys was studied. The ball milled
samples exhibited coexisting austenite and martensite phases at room
temperature, while annealing supresses the austenite phase completely. Ball
milling was found to reduce the grain size, which resulted in the weakening of
the ferromagnetic properties. An exchange bias field of 111 Oe and coercivity
of 826 Oe were observed at 5 K in the as-milled sample, in contrast to the bulk
alloy values of 288 Oe and 292 Oe, respectively. Annealing causes an increase
in the ferromagnetic ordering and a decrease in the interfacial exchange
coupling, resulting in a decrease of both exchange bias and coercivity.
