  In the lifetime of a magnetic refrigerator the materials are subjected to
millions of thermal magnetic cycles, so it is of the utmost importance to
predict the behavior of such materials when subjected to related work
conditions. Thus, in this work we investigated the influence of thermal cycling
in the microstructure, magnetic phase transition and magnetic entropy change of
a Gd5Si1.3Ge2.7 thin film up to 1000 cycles. In a first stage, till 450 cycles,
the hysteresis area of the magnetization curves as a function of temperature
was found to decrease 16% with thermal cycling, due to an arresting of the
O(II) phase caused by internal strain. Nonetheless, after 1000 cycles there is
a clear loss of the magneto-structural transition. For all thermal cycles the
O(I) phase remains unchanged. Therefore, prolonged thermal cycling leads to a
strong reduction of the O(II) phase, attributed to an internal pressure
build-up, caused by the large number of expansion/compression cycles that the
O(II) phase undergoes across the magnetostructural transition.

Materials Science