  Nanocrystalline ribbons of inverse Heusler alloy Mn2Ni1.6Sn0.4 have been
synthesised by melt spinning of the arc melted bulk precursor. The single phase
ribbons crystallize into a cubic structure and exhibit very fine crystallite
size of < 2 nm. Temperature dependent magnetization (M-T) measurements reveal
that austenite (A)-martensite (M) phase transition begins at T~248 K and
finishes at T~238 K during cooling cycle and these values increase to T~267 K
and T~259 K while warming. In cooling cycle, the A-phase shows ferromagnetic
(FM) ordering with a Curie temperature T~267 K, while both the
FM-antiferromagnetic (AFM) and M-transitions occur at T~242 K. The M-phase
undergoes FM transition at T~145 K. These transitions are also confirmed by
temperature dependent resistivity measurements. The observed hysteretic
behaviour of magnetization and resistivity in the temperature regime spanned by
the A-M transition is a manifestation of the first order phase transition.
Magnetization and susceptibility data also provide unambiguous evidence in
favour of spin glass . The scaling of the glass freezing temperature (Tf) with
frequency, extracted from the frequency dependent AC susceptibility
measurements, confirms the existence of canonical spin glass at T<145 K. The
occurrence of canonical spin glass has been explained in terms of the
nanostructuring modified interactions between the FM correlations in the
martensitic phase and the coexisting AFM.
