Abstract
La1.3−xYxSr1.7Mn2O7 (x = 0, 0.025) samples are prepared by the conventional solid-state reaction. X-ray diffraction spectrum reveals that the samples are in the Sr3Ti2O7-type tetragonal phase with the space group I4/mmm. By decreasing the temperature, two samples exhibit the paramagnetic phase at high temperatures to two-dimensional short-range-ordered ferromagnetic states at the intermediate temperatures and finally three-dimensional long-range-ordered ferromagnetic states. Furthermore, the doped sample also demonstrates antiferromagnetic ordering in the low-temperature region. The Arrott curve and calibration curve indicate that the sample behaves as a first-order phase transition. When the applied magnetic field is 6 T, the maximum magnetic entropy change ($$\Delta S_{M}$$) occurs in the two samples in the vicinity of the three-dimensional ordered temperature (Tc3D), and the value of $$\Delta S_{M}$$ for the two samples reaches—4.81 J/kg K and—3.82 J/kg K, respectively. In addition, the relative cooling power is 108 J/kg and 112.2 J/kg at $$\mu_{0} H = 3\;T$$, respectively. Although the doping of Y reduces Tc3D, $$\Delta S_{M}$$ and the first-order phase transition character, the relative cooling power is enhanced, thus indicating its potential to realize magnetic refrigeration in high-temperature regions (T > 77 K).
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