  The temperature dependent crystal structure analysis in martensitic phase of
Ni_2Mn_(1+x)Sn_(1-x) (x = 0.40 and 0.44) magnetic shape memory alloy is
performed using X-ray diffraction. The martensitic phase consists of 4-Layered
and 14-Layered orthorhombic structure. The phase fraction of 4-layered and
14-layered orthorhombic structure change with temperature. Interestingly, the
magnetic property also changes with temperature and corresponds to structural
change temperature. Thus, the exchange coupling constant between original Mn
and substituted Mn is calculated, which shows that the 4-layered and 14-layered
orthorhombic structures have different strength of antiferromagnetic coupling.
The analysis explain the origin of spin glass behavior and unusual exchange
bias effect in these systems under zero-field-cooling.
