  The ground state properties of the ferromagnetic shape memory alloy of
nominal composition Ni2Mn1.36Sn0.64 have been studied by dc magnetization and
ac susceptibility measurements. Like few other Ni-Mn based alloys, this sample
exhibits exchange bias phenomenon. The observed exchange bias pinning was found
to originate right from the temperature where a step-like anomaly is present in
the zero-field-cooled magnetization data. The ac susceptibility study indicates
the onset of spin glass freezing near this step-like anomaly with clear
frequency shift. The sample can be identified as a reentrant spin glass with
both ferromagnetic and glassy phases coexisting together at low temperature at
least in the field-cooled state. The result provides us an comprehensive view
to identify the magnetic character of various Ni-Mn-based shape memory alloys
with competing magnetic interactions.
