X-ray diffraction pattern of the Fe-0 sample. The Bragg peaks can be associated with the -type structure. Inset figure shows a SEM image recorded from a polished surface of the Fe-7 sample.
curves of the alloys obtained at 50 mT (left-hand side—a, c, e, g, i) and 5 T (right-hand side—b, d, f, h, j). The samples are labeled , where is related to the Fe content.
Magnetic and crystallographic phase diagram as a function of Fe content in Heusler alloys. PM, FM, and respectively means paramagnetic, ferromagnetic phases, and martensitic Curie temperature.
(a) Isothermal magnetization curves for the (a) Fe-0 and (b) Fe-7 samples at different temperatures. For clarity only three different symbols are used in three temperature intervals where high-field is nearly monotonic. In the contrary, several temperatures are indicated in Fig. 4(b).
loops recorded at 5 K for the (a) Fe-0, (b) Fe-3, (c) Fe-7, and (d) Fe-10 samples after the materials have been cooled down from 320 K under an applied field of 20 kOe. The insets show the central part of the hysteresis loops to better visualize the loop horizontal shift.
(a) and (b) field values obtained at different temperatures (region of the EB effect) for the Fe-0, Fe-3, and Fe-7 samples cooled under field of 20 kOe.
loops recorded at (a) 50 K and (b) 160 K for the Fe-0 sample after the material has been cooled down to 5 K from 320 K under an applied field of 20 kOe. Figure 7(a) inset shows the spin-flip effect observed for temperatures close to those where the field goes to zero.
Temperature dependence of the magnetic entropy change under different magnetic field variation (up to 5 T) for the (a) Fe-7 sample and (b) magnetic entropy change under a variation of 5 T for the Fe-0, Fe-3, and Fe-7 samples. The arrow in (b) indicates the magnetic entropy change due to the FM-PM phase transition of the austenitic state of the Fe-0 sample.
From left to right columns: values of the Curie temperature of austenitic and martensitic phases; initial and final austenitic and/or martensitic transition temperatures, their transition temperature widths [ and ], and the martensitic phase transition parameter .
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