Influence of Annealing Conditions on Magnetic Properties, Magnetocaloric Effect, and Critical Parameters of Ni–Mn–Sn Ribbons

In this paper, we investigated the influence of annealing conditions on magnetic properties, magnetocaloric effect, and critical parameters of Ni
₅₀
Mn
_50-x
Sn
_x
(x = 13, 13.5, and 14) alloy ribbons prepared by using the melt-spinning method. The ribbons were annealed at 1123 K for various times. A martensitic-austenitic (M-A) structural phase transformation was observed on both the as-quenched and annealed samples. Temperature of the M-A phase transition (T
_M-A
) of the ribbons can be regulated in room temperature region by changing the annealing time. Maximum positive and negative magnetic entropy changes, |AS
_m
|
_max
, larger than 3 and 1 J · kg
^-1
· K
^-1
, respectively, were achieved on the Ni
₅₀
Mn
₃₇
Sn
₁₃
sample after annealing for 0.5 h. Critical parameters were determined to elucidate magnetic orders in the alloy. The obtained parameters are very close to those of the mean field theory of long-range ferromagnetic orders.